Massive TPS drop after about 5 or 6 people come on

[James070508]

Server specs:

And the amount of people on at this time? Just 7. We sometimes take on about 23 people during saturday night, so surely this isn't an issue where the server is incapable.

The server runs through Multicraft.

A few things I'd like to point out from these images are...

The RAM constantly goes from like 300MB to 1300MB. (Maybe NoLagg?Idk)

The TPS is at 4.15? Waaay too low.

When I ask people "Rate the lag, with 1 being no lag and 10 being loads of lag" They usually respond with 2 - 4. However,world loading seems slow.

Our list of plugins are...

The last thing I think I did to the server before this occured was install bPermissions, my bPermissions set up is... I don't want to uninstall it as its a widely used plugin, why would it be a direct cause of lag? Maybe incompatibilities? Plus it would ruin some worlds and staff ranks if I uninstall.

Config - http://pastebin.com/KqYjKfxG

Groups - http://pastebin.com/KKN5d93b

How is the TPS so low? It stays at a solid 20TPS until like 5 or 6 people get on. Will send through any console info when I see it.

This is all the info that i think you will need, however, if you need anything else, reply and I'll post back ASAP.

Thanks

------------------------------------------------------------------------------------------------------

UPDATE

Our TPS just bounced back to 20tps. It will go back down again. I still need it fixed.

Within the servers uptime (3 hours) it goes from 20TPS, to 4tps, then back to 20. At this point, we have 9 people on. It stayed on 20tps for about a day, with near enough nobody on, we are at 3.17tps now.