I am not very good in reading crashlogs and the spark stuff but when i try to put disks inside the extended ae io port sometimes the server crashes or lags out like for this time.

Server crashlog : https://mclo.gs/l6tTBeH

Spark Screenshot:

If you want any other infos lmk.

AE's IO port with full acceleration cards can move 2048 items/tick, and Extended IO port with 2 cards is 8192 items/tick.

I can understand your point and to be clear I don't have the full 5 acceleration cards in. I do gave only 5 installed and a redstone card to control it when it should move items.
When I use the normal AE2 IO port I don't have any problems but then only with 2 acceleration cards and one redstone card.

I'll blame functional storage's drawer controller. It isn't performanent enough to deal with AE's throughput, and causes huge lag.

Seem they has fixed this issue.