https://forums.dovetailgames.com/threads/please-optimize-tsw4-engine-ini.73687/#post-721655

Using Kessell to Würzburg as my test route, Goloxo engine.ini looks great but bogged down to under 30 FPS in some parts. I adjusted values as suggested in the above link and got another 10 FPS.

The dbrunner engine.ini runs near constant 50-60 FPS, but the draw distance is not as good and shadows pop in closer.

Default engine.ini runs at high 50's with short shadow pop in.

Found Shadow Quality has a big impact on FPS

On some routes (eg Southeast Coast Line) I get a steady 60 FPS with Shadow Quality set to high.

Recommend using Geloxo engine.ini-MyModification (stored on Google Drive) and adjust Shadow Quality in TSW4 to suit.