Tps drop (Pixelmon)

Hello i have a pixelmon server, and some times my server gets slow and not playable.
could you help me?

the server has 5, max 10 players online

these are the timings

Ram: 8 gb
Cpu: Intel® Xeon® CPU E5-2630 v4 @ 2.20GHz

hello, i have pre-generated my worlds, but the server doesn’t stop to drop tps.

any advice?