tong uses all the CPU time it can get because of a loop without a timer. The proposed patch limits the frame rate to 22.2, thus reducing CPU load without any impact on gameplay. I will also send the patch to the developer. However, I'm not sure whether there is still development on this game, so I suggest adding this patch until the issue is resolved upstream.
Created attachment 133594 [details, diff] Patch to limit fps to 22.2
Created attachment 133595 [details, diff] patch from tong-1.0.ebuild to tong-1.0-r1.ebuild
patch is in portage. re-emerge to get it if the cpu load matters.