There’s some diagnostic info when in game through the battery sidebar menu, I think. You can use that to see frame rate and other performance benchmarks.
I usually just google or YouTube some way to improve whatever game I’m playing on deck. Usually, someone has already done the leg work to figure it out.
I couldn’t find the game’s link in the article, so here it is for others: https://store.steampowered.com/app/2468250/silkbulb_test/#:~:text=Silkbulb Test is a co,from grinding to a halt