Hi,
I noticed this in a few stores, after a few minutes my client starts lagging for no reason, usually it only lags if a certain corner of the shop is in my viewfield though. Theres nothing special in these corners, just normal prims that have buy option.
When I change my graphic settings it goes away (doesn't matter if i change then from low to high or high to low) for a few minutes and then comes back, however when i do that 1 or 2 times it doesn't make it go away anymore then.
Fast timers tells me Full Bright eats lots of time (on Emerald) on the normal client it was some triangle vertex thingy