I can't open the guidebook without a lagspike; the client freezes for about 15-20 seconds before opening the guidebook.

BuildCraft version: 7.99.17
Forge version: 2747
Link to crash report or log: n/a
Singleplayer or multiplayer: Multiplayer
Steps to reproduce: Open the Guidebook
Additional information: n/a

For me it's about 2-5 seconds, but it is a thing.

I opened it about 4 times in 2 worlds.

I'm not entirely sure where the performance issue is so I'll add some profiling to 7.99.18-pre1 and then ask you to send the resulting profiler logs back here. It will probably take a few days to come out though.

After a bit of analysis it looks like it scans the item and statement registries everytime you open the gui, and populates a search object, which takes up quite a while. I'll try moving that code to the main reload() sequence to see if that speeds it up a bit.

Many thanks.

This should be fixed in the 7.99.18-pre1 prerelease, or you can wait until 7.99.18 itself gets released.