Environment:
Minecraft 1.10.2
Forge 12.18.3.2221
Botania r1.9-340
Baubles 1.10.2-1.3.9
and nothing else.

Issue: Holding a wand of the forest to visualise mana bursts (wand beam) near a large number of mana spreaders equipped with composite Bore Warp lenses (green version) results in a large FPS drop. The same number of spreaders without the lenses causes no significant FPS drop. Higher tier spreaders cause correspondingly more FPS drop due to longer bursts.

Note: Further testing shows that possibly any lens (plain Bore, plain Warp and even just a plain Mana Lens) will result in similar FPS drop, as long as the mana burst, and hence the wand beam, is not interrupted. Composite bore warp lenses are particularly a problem because the full length of the mana burst is always visualised while holding a wand of the forest, irrespective of intervening blocks such as mana pools or other spreaders.

Steps to reproduce:

• Create a new superflat redstone-ready preset world.
• Place down about 64 mana spreaders (or higher tier spreaders) in rows of 32, stacked 2 high, facing forward.
• Equip wand of the forest, note FPS (baseline).
• Place composite bore warp lenses (look like bore lenses) on the mana spreaders.
• Equip wand of the forest, note FPS (reduced).
• Place mana pools directly in front of all mana spreaders
• Equip wand of the forest, note FPS (still reduced).

Config settings (changes from default, but also tested with default):
B:blockBreakingParticles.enabled=false
B:powerSystem.subtle=true
B:shaders.enabled=false
Particles: Minimal (minecraft video settings)

Background: I discovered this while trying to build a system involving 136 gaia spreaders with bore warp lenses and force relays to mine blood magic meteors generated by the mark of the falling tower ritual.