Hello everyone,

I have an older windows 7 machine I like to play cuphead on for the CRT glory!

It's a core2quad Q6600 @ 2.8GHz with 8GB of RAM.

Running the older build 15295 from Sept 2017 runs perfect. Butter smooth no lag or stutters. Uses 15-20% total cpu usage.

If I install the current available version 29705 it lags and runs horrible. Single digit framerates with 0.5-1 second pauses. Watching task manager shows 100% cpu usage across all four cores!

Luckilly I archive all my installers and was able to go back to the older build Butter smooth again.

Did the real system requirements go up with the newer build? GOG and Steam still show the requirements at a dual core!

Anyone else using older hardware successfully running this game on the current build? Any ideas of what could have changed?

Two years later I'm coming back to answer my own question :D
I put this info out there so that hopefully someone in the retro gaming community will see this and know what is happening.

TL;DR:
Unity Game engine updates released within the past few years require more recent graphics adapters then the official requirements let on.

The official system requirements as of today. As far as I am aware these have not been updated since Cuphead originally released:
CPU: Intel Core2 Duo E8400 3.0GHz or AMD Athlon 64 X2 6000+ 3.0GHz or higher
GPU: GeForce 9600 GT or AMD HD 3870 512MB or higher

I had multiple systems on which I ran Cuphead:
Core 2 Quad 6600 w/ ATI X1900 crossfire: unplayable stutter mess with 100% cpu usage across all four cores
Core 2 Quad 9450 w/ GeForce 9600GT: slow with pauses and nearly 100% cpu usage across all four cores
Lenovo 11e m3 8100y: playing via proton it was pretty ok at low resolutions (800x600).
Steam Deck: no problems with running the GOG version via proton.
All my other newer more powerful systems played it butter smooth, no issues - the slowest being an i5 4690 w/ GeForce 560ti.
(Before you judge too harshly, the Q6600 system is my old personal gaming PC I built in 2007 and the Q9450 system is cobbled together used parts for my 5 year old son.)

I did some testing with the Q6600. I changed the X1900 cards out for a single AMD HD6950 I had laying around (note this is the card from 2011, not 2021!). All of a sudden Cuphead is silky smooth with no slowdowns or stutters! CPU utilization is also low. I fired up Dusk which is another Unity engine game which had the same problem and it's now perfectly playable! Building on that success I swapped the card in the Q9450 machine from the 9600GT to a Quadro K2000. That computer also now can play Cuphead silky smooth with normal low cpu utilization!

ATI X1900: DX9 (2006)
GeForce 9600GT: DX10 (2008)
AMD HD6950: DX11 (2011)
Quadro K2000: DX12 (2013)

Final summary: My assumption is something changed with the system requirements for the Unity game engine releases that have occurred after the original retail releases of both Cuphead and Dusk. My guess is that Unity added some graphics API calls which are missing from older graphics hardware. This is causing the Unity engine to fall back to software rendering which is overwhelming the CPU. A newer GPU - at least DX11 class hardware - will properly accelerate the graphics and bring the CPU usage back down to normal.