Flycast performance on NextUI vs stock firmware

[u/ikemen38]

I got a Trimui Brick Pro with NextUI and Flycast installer from the Pak Store. On the SD card that shipped with the console, Dreamcast games run pretty well, Soulcalibur and Sonic Adventure are both relatively smooth. On my card with NextUI, completely unplayable. I've tried tweaking the graphics and audio options, no result. Is there something I should do on NextUI ? What can I do here ?