I noticed a couple of things that slow down the game:
- maybe it seemed to me, but the game starts to freeze because of developing relationships with all the girls, that is, the more you develop relationships and stats to the maximum, the more the game starts to freeze (I mean you pumped everything up to the maximum and then the meeting events in locations start to trigger and there can be so many of them that this process becomes uncontrollable because the priorities are unclear)
- or because of old, unoptimized code in the very first characters
I'd wager the argument that it's both; Unoptimized and or older code combined with newer code/girls. Hold shift+g then change your settings; According to google the Angle render plugins are for windows, the GL is merely Open-GL however I didn't see too much of a difference between what I render & changing my frame rate from 30/60/screen turning power save to off gave me a mild speed boost.
I'd argue get some help but most people wont touch this game with dozens of ten foot poles strung together due to how much of a fuckery it is to recode it all.
The issue of the 'extreme choppiness' of the modded version definitely lies in the code added by the mod:
Once you start the latest version of the mod (Rogue-Like-1.54c-3-mod), the GPU utilization of your machine will spike to ~100% and is kept at ~100% usage constantly. If you start a vanilla game (Rogue-Like-1.54c-win) you do not see this spike and constant usage.
Most probably some 'draw routine' of the modded version, that was adjusted/added for the mod, will cause this issue.
This constant 100% GPU usage and the unoptimized code of the vanilla game makes the mod 'extremely choppy'. Changing the renpy renderer won't resolve this.
Once the GPU issue is fixed, mod and vanilla should have a rather 'similar choppiness'.
I've attached 2 screenshots below (modded & vanilla), where you will see the GPU usage of my machine using HWMonitor.
If you start the game on your local machine, just use your Task-Manager, Process Explorer or monitoring application of your choice to see the GPU usage issue...