Okay, so I played Thunder for an half an hour or so and here's what I think needs to be fixed.
1) The sky is moving WAY too fast. I got dizzy just looking at it.
2) Some doors open and some don't and it's confusing as hell.
3) I like the atmosphere a lot and the shadows are great, but I think some places are too dark.
4) Obviously there're no bot support yet.
Yup, although it is excessively bright compared to the other maps. I usually have to turn up my gamma for them, but this one looks entirely white when viewed with above-average gamma. I'm not saying this is bad (In fact, this should be the norm), but it is helpful to have internally-consistent brightness of maps so I don't have to adjust my gamma in-game.
If the map looks like you have no light (very bright, no shadows) this is the lack of lightmaps loading. You probably have to update your libwebp to fix this.
About FPS there are a few things you can do. You can disable bumpmapping with r_normalmapping 0. Make sure r_bloom and r_hdrrendering off too. Also disable any multisampling. You could always try the vanilla renderer besides these also...