Short freezes on Cubase playback when using Scope Reverb?

[Mydriasis]

Im using Cubase 4 and have my Scope card setup so audio is routed out via ADAT and back into my RME Fireface (which is the main audio interface im using)
RME set as master, Pulsar as slave. All synced up

The audio from Scope goes into Cubase, just like i were using hardware/outboard synths and fx.

The problem ive noticed is that Cubase will freeze up for 3-4 seconds on playback, it happens exporting too

Although it only seems to do this when i have Scope reverbs loaded?

Just wondering if anyone else has had this problem or knows about it?
Any help to stop it doing this will be really appreciated!

[Mydriasis]

Thanks for the reply

So only Scope reverbs require PCI to memory? Or will other devices like synths cause this too?

Im also using 2x UAD PCIE cards and a TC Powercore PCI card so perhaps they're not helping...
Motherboard is Intel DP35

I'll look at my Cubase and XP settings.. So Cubase Preload time i think ive seen under the menus.
But XP CPU time usage time? im not sure where to find that?

[at0m]

Delays and samples use your DAW's RAM (over PCI), but that's nothing compared to the >200 delay lines used in some reverbs...