Here at RetroArch/libretro, we have always insisted on catering to both the low-end as well as the high end. To further this purpose, we always make design considerations from this perspective, that whatever we do shouldn’t be at the cost of worse performance on lower specced hardware that we still support.

Newer generation emulators are increasingly catering to the high end and almost demand it by virtue of them being based on much more recent videogame systems. While testing RetroArch and various libretro cores on our new high-end Windows desktop PC, we noticed that we could really take things up a few notches to see what we could get out of the hardware.

Dolphin

While working on the Dolphin libretro core some more, we stumbled upon the issue that internal resolution increases were still not working properly. So while fixing that in the latest core, we felt that the default scaled resolution choices that Dolphin provides (up to 8x native resolution) weren’t really putting any stress on our Windows development box (a Core i7 7700K equipped with a Titan XP).

So, in the process we added some additional resolution options so you can get up to 12K. The highest possible resolution right now is 19x (12160×10032).

As for performance results, even at the highest 19x resolution, the average framerate was still around 81fps, although there were some frame drops here and there and I found it to be generally more safe to dial the internal resolution down to a more conservative 12x or 15x instead). 12x resolution would be 8680×6336, which is still well over 8K resolution.

Note that the screenshots here are compressed and they are downscaled to 4K resolution, which is my desktop resolution. This desktop resolution in turn is an Nvidia DSR custom resolution, so it effectively is a 4K resolution downsampled to my 1080p monitor. From that, I am running RetroArch with the Dolphin core. With RetroArch, downscaling is pretty much implicit and works on the fly, so through setting the internal resolution of the EFB framebuffer, I can go beyond 4K (unlike most games which just query the available desktop resolutions).

We ran some performance tests on Soul Calibur 2 with an uncapped framerate. Test box is a Core i7 7700k with 16GB of DDR4 3000MHz RAM, and an Nvidia Titan XP video card. We start out with the base 8x (slightly above 4K Ultra HD) resolution which is the highest integer scaled resolution that Dolphin usually supports. If you want to go beyond that on regular Dolphin, you have to input a custom resolution. Instead, we made the native resolution scales go all the way up to 19x.

On the Nvidia Control panel, nearly everything is maxed out – 8x anti-aliasing, MFAA, 16x Anisotropic filtering, FXAA, etc.

Resolution	Performance (with OpenGL)	Performance (with Vulkan)
8x (5120×4224) [for 5K]	166fps	192fps
9x (5760×4752)	165fps	192fps
10x (6400×5280)	164fps	196fps
11x (7040×5808)	163fps	197fps
12x (7680×6336) [for 8K]	161fps	193fps
13x (8320×6864)	155fps	193fps
14x (8960×7392)	152fps	193fps
15x (9600×7920) [for 9K]	139fps	193fps
16x (10240×8448) [for 10K]	126fps	172fps
17x (10880×8976)	115fps	152fps
18x (11520×9504) [for 12K]	102fps	137fps
19x (12160×10032)	93.4fps	123fps

OpenLara

The OpenLara core was previously capped at 1440p (2560×1440). We have added available resolutions now of up to 16K.

Resolution	Performance
2560×1440 [for 1440p/2K]	642fps
3840×2160 [for 4K]	551fps
7680×4320 [for 8K]	407fps
15360×8640 [for 16K]	191fps
16000×9000	176fps

Craft

Previously, the Craft core supported only up to 1440p. Now it supports up to 16K and slightly higher.

For the Craft core, we are setting the ‘draw distance’ to 32, which is the highest available draw distance available to this core. With the draw distance set this far back, you can even see some pop-in right now (terrain that is not yet rendered and will only be rendered/shown when the viewer is closer in proximity to it).

Resolution	Performance
2560×1600 [for 1440p/2K]	720fps
3840×2160 [for 4K]	646fps
7680×4320 [for 8K]	441fps
15360×8640 [for 16K]	190fps
16000×9000	168fps

Parallel N64 – Angrylion software renderer

So accurate software-based emulation of the N64 has remained an elusive pipe dream for decades. However, it seems things are finally changing now on high-end hardware.

This test was conducted on an Intel i7 7700K running at Boost Mode (4.80GHz). We are using both the OpenGL video driver and the Vulkan video driver for this test, and we are running the game Super Mario 64. The exact spot we are testing at it is at the Princess Peach castle courtyard.

Super Mario 64

Description	Performance (with OpenGL)	Performance (with Vulkan)
Angrylion [no VI filter]	73fps	75fps
Angrylion [with VI filter]	61fps	63fps

Quake 64

Description	Performance (with OpenGL)	Performance (with Vulkan)
Angrylion [no VI filter]	81fps	82.5fps
Angrylion [with VI filter]	68fps	72fps

Killer Instinct Gold

Description	Performance (with OpenGL)	Performance (with Vulkan)
Angrylion [no VI filter]	57.9fps	58.7fps
Angrylion [with VI filter]	54.6fps	55fps

GoldenEye 007

Tested at the Dam level – beginning

Description	Performance (with OpenGL)	Performance (with Vulkan)
Angrylion [no VI filter]	54.9fps	43.8fps
Angrylion [with VI filter]	45.6fps	40.9fps

Note that we are using the cxd4 RSP interpreter which, despite the SSE optimizations, would still be pretty slow compared to any RSP dynarec, so these results are impressive to say the least. There are games which dip more than this – for instance, Killer Instinct Gold can run at 48fps on the logo title screen, but on average, if you turn off VI filtering, most games should run at fullspeed with this configuration.

In case you didn’t notice already, Vulkan doesn’t really benefit us much when we do plain software rendering. We are talking maybe a conservative 3fps increase with VI filtering, and about 2fps or maybe even a bit less with VI turned off. Not much to brag about but it could help in case you barely get 60fps and you need a 2+ fps dip to avoid v-sync stutters.

Oddly enough, the sole exception to this is GoldenEye 007, where the tables are actually turned, and OpenGL actually leaps ahead of Vulkan quite significantly, conservatively by about 5fps with VI filter applied, and even higher with no VI filter. I tested this many times over to see if there was maybe a slight discrepancy going on, but I got the exact same results each and every time.

Parallel N64 – Parallel Vulkan renderer

So we have seen how software-based LLE RDP rendering runs. This puts all the workload on the CPU. So what if we reverse the situation and put it all on the GPU instead? That is essentially the promise of the Parallel Vulkan renderer. So let’s run the same tests on it.

This test was conducted on an Intel i7 7700K running at Boost Mode (4.80GHz). We are using the Vulkan video driver for this test, and we are running the game Super Mario 64. The exact spot we are testing at it is at the Princess Peach castle courtyard.

Super Mario 64

Description	Performance
With synchronous RDP	192fps
Without synchronous RDP	222fps

Quake 64

Description	Performance
With synchronous RDP	180fps
Without synchronous RDP	220fps

Killer Instinct Gold

Description	Performance
With synchronous RDP	174fps
Without synchronous RDP	214fps

GoldenEye 007

Tested at the Dam level – beginning

Description	Performance
With synchronous RDP	88fps
Without synchronous RDP	118fps

As you can see, performance nearly doubles when going from Angrylion to Parallel renderer with synchronous RDP enabled, and beyond with it disabled. Do note that asynchronous RDP is regarded as a hack and it can result in many framebuffer oriented glitches among other things, so it’s best to run with synchronous RDP for best results.

We are certain that by using the LLVM RSP dynarec, the performance difference between Angrylion and Parallel would widen even further. Even though there are still a few glitches and omissions in the Parallel renderer compared to Angrylion, it’s clear that there is a lot of promise to this approach of putting the RDP on the GPU.

Conclusion: It’s quite clear that even on a quad-core 4.8GHz i7 CPU, the CPU ‘nearly’ manages to run most games with Angrylion [software] at fullspeed but it doesn’t leave you with a lot of headroom really. Moving it to the GPU [through Parallel RDP] results in a doubling of performance with the conservative synchronous option enabled and even more if you decide to go with asynchronous mode (buggier but faster).

Beetle PSX

Previously, Beetle PSX would only provide internal resolution increases up to 8 times the original resolution. We have now extended this to 32 x for software and Vulkan, and 16x for OpenGL.

The results are surprising – while the Vulkan renderer is far more mature than the OpenGL renderer and implements the mask bit unlike the GL renderer (along with some other missing bits in the current GL renderer), the GL renderer leaps ahead in terms of performance at nearly every resolution.

Crash Bandicoot

Crash Bandicoot is a game that ran at a resolution of 512×240.

Resolution	Performance (with OpenGL) [with PGXP]	Performance (with OpenGL) [w/o PGXP]	Performance (with Vulkan) [with PGXP]	Performance (with Vulkan) [w/o PGXP]	Performance (software OpenGL)	Performance (software Vulkan)
8192×3840 [16x] [for 5K]	188.8fps	266fps	217fps	239fps	4.4fps	5.3fps
4096×1920 [8x] [for 2K]	216fps	296fps	218fps	240fps	16fps	17.5fps
2048×960 [4x]	215fps	296fps	216fps	239fps	52fps	57.9fps
1024×480 [2x]	216fps	296fps	216fps	239fps	138fps	145fps

Tekken 3

Tekken 3 is a game that ran at a resolution of 368×480.

Resolution	Performance (with OpenGL) [with PGXP]	Performance (with OpenGL) [w/o PGXP]	Performance (with Vulkan) [with PGXP]	Performance (with Vulkan) [w/o PGXP]	Performance (software OpenGL)	Performance (software Vulkan)
11776×15360 [32x] [for 12K]	N/A	N/A	127fps	127.4fps	N/A	N/A
5888×7680 [16x] [for 4K]	188.5fps	266fps	184.4fps	211fps	4.4fps	6.6fps
2944×3840 [8x] [for 2K]	186.5fps	208fps	183.5fps	269fps	22fps	25.2fps
1472×1920 [4x]	184.5fps	270fps	230.5fps	210fps	52fps	59.4fps
1024×480 [2x]	232fps	271fps	185.5fps	210fps	129fps	137fps

Reicast

Dead or Alive 2

Description	Performance
4480×3360	206fps
5120×3840	206fps
5760×4320	206fps
6400×4800	204fps
7040×5280	206fps
7680×5760	206fps
8320×6240	204fps
8960×6720	204fps
9600×7200	207fps
10240×7680	206fps
10880×8160	207fps
11520×8640	207fps
12160×9120	194fps
12800×9600	193fps

As you can see, it isn’t until we reach 12160×9120 that Reicast’s performance finally lets up from an almost consistent 206/207fps to a somewhat lower value. Do note that this was testing the same environment. When alpha effects and RTT (Render to Texture) effects are being applied onscreen, there may well be dips on the higher than 8K resolutions whereas 8K and below would be able to handle it with relative ease.

Mupen64plus – GlideN64 OpenGL renderer

This core uses Mupen64plus as the core emulator plus the GlideN64 OpenGL renderer.

Super Mario 64

Description	Performance
3840×2880 – no MSAA	617fps
3840×2880 – 2x/4x MSAA	181fps
4160×3120 – no MSAA	568fps
4160×3120 – 2x/4x MSAA	112fps
4480×3360 – no MSAA	538fps
4480×3360 – 2x/4x MSAA	103fps
4800×3600 – no MSAA	524fps
4800×3600 – 2x/4x MSAA	94fps
5120×3840 – no MSAA	486fps
5120×3840 – 2x/4x MSAA	82fps
5440×4080 – no MSAA	199fps
5440×4080 – 2x/4x MSAA	80fps
5760×4320 – no MSAA	194fs
5760×4320 – 2x/4x MSAA	74fps
6080×4560 – no MSAA	190fps
6080×4560 – 2x/4x MSAA	68fps
6400×4800 – no MSAA	186fps
6400×4800 – 2x/4x MSAA	61.3fps
7680×4320 – no MSAA	183fps
7680×4320 – 2x/4x MSAA	39.4fps

GoldenEye 007

Tested at the Dam level – beginning

Description	Performance
3840×2880 – no MSAA	406fps
3840×2880 – 2x/4x MSAA	100fps
4160×3120 – no MSAA	397fps
4160×3120 – 2x/4x MSAA	65fps
4480×3360 – no MSAA	375fps
4480×3360 – 2x/4x MSAA	60fps
4800×3600 – no MSAA	342fps
4800×3600 – 2x/4x MSAA	54fps
5120×3840 – no MSAA	310fps
5120×3840 – 2x/4x MSAA	51fps
5440×4080 – no MSAA	70fps
5440×4080 – 2x/4x MSAA	46fps
5760×4320 – no MSAA	78.9fs
5760×4320 – 2x/4x MSAA	42fps
6080×4560 – no MSAA	86fps
6080×4560 – 2x/4x MSAA	37fps
6400×4800 – no MSAA	79fps
6400×4800 – 2x/4x MSAA	27fps
7680×4320 – no MSAA	79fps
7680×4320 – 2x/4x MSAA	33.2fps

Preface: Immediately after going beyond 3840×2880 (the slightly-higher than 4K resolution), we notice that turning on MSAA results in several black solid colored strips being rendered where there should be textures and geometry. Again, we notice that enabling MSAA takes a huge performance hit. It doesn’t matter either if you apply 2 or 4 samples, it is uniformly slow. We also notice several rendering bottlenecks in throughput – as soon as we move from 5120×3840 to 5440×4080 (a relatively minor bump), we go from 310fps to suddenly 70fps – a huge dropoff point. Suffice to say, while you can play with Reicast (Dreamcast emulator) and Dolphin (Gamecube/Wii) at 8K without effort and even have enough headroom to go all the way to 12K, don’t try this anytime soon with Gliden64.

We suspect there are several huge bottlenecks in this renderer that prevent it from reaching higher performance, especially since people on 1060s have also complained about less than stellar performance. That being said, there are certain advantages to Gliden64 vs. Glide64, it emulates certain FBO effects which GLide64 doesn’t. It also is less accurate than Glide64 in other areas, so you have to pick your poison on a per-game basis.

We still believe that the future of N64 emulation relies more on accurate renderers like Parallel RDP which are not riddled with per-game hacks vs. the traditional HLE RDP approach as seen in Gliden64 and Glide64. Nevertheless, people love their internal resolution upscaling, so there will always exist a builtin audience for these renderers, and it’s always nice to be able to have choices.