Possibly same issue as #233
According to the F3 debug chart, the render lag appears under root.gameRender.level.terrain_setup. After testing, determined the RS system was the source, specifically the external storage attached to the drawer system. While attempting to reproduce, I determined it occurs when my disk drive has a differing priority form the external storage, and an exporter is exporting items contained in the drawers

• Minecraft: 1.10.2
• Forge build 2066
• Refined Storage: 0.8.20
  -Storage Drawers: 3.2.5

Same here. I thought it was an item in my storage draws, but after removing 1 draw at a time my performance never got better. The only way is if I cut of the connection to the external storage and everything runs fine.

Send me a .nps profiling file so I can see where the bottleneck is, thanks.

profile
sorry, took me a bit to get back, github didn't send a notification email :/

This still happens on the latest version of this mod

I think what happened is OP managed to hit the performance threshold of what a binary sort can handle; you may want to use a more scalable algorithm.

And where would this binary sort be?

Looking at the nps file, it seems like Storage Drawers is triggering render updates, which would cause the client lag.

I can't reproduce this on the latest Storage Drawers & RS Beta versions...