Even on my high-end PC, I have noticed significant lag spikes during chunkload while changing dimensions, which is nowhere near as severe without the mod.

This also appears when first loading into a world (which isn't that severe without the mod)

JVM and Java Configuration is default with 8GB Ram allocated. I'm not home right now but when I am, I will send a log file.

Can you provide logs, mod list, jvm and java configuration, hardware specifications.

Closed as the issue cannot be reproduced.