k shep, TJM623, there could be a couple of issues, so let's try and flesh this out. First how much ram did you have before the upgrade and how much total did you upgrade too?
The E1505 is like most notebooks sold at that time as it only supports 2gigs of RAM. Ideally you want 2 - 1gig sticks for maximum performance so the memory controller can operate interleaved in dual channel mode.
You may be able to physically install more RAM than the 2 - 1gig modules, but this creates problems/slowdowns elsewhere. First, if the memory controller can only cache up to 2 gigs of memory or the BIOS only recognizes this amount, then any RAM above that amount remains uncached. Since memory gets mapped downward from the highest address space first (exception being memory blocks below the 540K region, a relic of DOS) but memory gets assigned to apps from the lower addresses to higher, it's quite possible that you're taking a severe hit because too many memory transactions are taking place outside of what's being cached by the memory controller.
Another more obvious answer is that you've got 2 unequal size (not speed) RAM modules so the controller isn't able to interleave them in dual-channel mode. Also something to consider, sometimes faster binned RAM has higher latency (more wait states) than slower. This is why a slower clock speed 200mhz module might be clocked 2-2-2 while a faster clocked 400mhz module might be 3-3-3.
The final thing to consider is what OS are you running? If you're running any 32bit flavor of Windows anything above 3 gigs is a waste (as in not used for apps), and for XP/32 at least, it's been shown consistently that the "sweet spot" for maximum performance is 2gigs. 64bit Windows are a different story and will suck-up all of the RAM it's given.
I hope this helps