The parameter dormantChunkCacheSize is set to 0 by default in ATM3R 1.5.3 in forgeChunkLoading.cfg. This causes regular lag spikes when using Compact Machines and under various other circumstances. Setting this to a small, but non-zero value would have little memory cost but can improve performance by a large degree for these cases.

Even setting a low value such as 8-16 would help in the default case.