I had really bad water lag after the update in gm_construct, like a lot of others did. Then i remebered that GiGaBiTe said something about water calling for a 7.vtf or a 8.vtf or a 6.vtf that isn’t real 1000 times every second, which is causing the lag. So, i made the 7, 8, and 6 vmt files, popped them in materials and, wow, no lag. My FPS was back up to 90.
Anyways, here are the files to fix the lag.
Credits to GiGaBiTe (Or was it someone else?) for finding this out.
Put this in your c:\Program Files\Steam\Steamapps\username\garrysmod\garrysmod folder.
Note: This just fixes the lag, not the white water or checkerboard water.