I very much doubt the spikes or lags can be attributed to the number of files in any given folder or even the number of files in your catalog, especially since your catalog and file count are fairly low. Also, your raw files are fairly small and not particularly taxing to a modern CPU. Therefore, I think your problem lies elsewhere.
Answers to a few questions might help generate ideas as to possible causes
Do you have Automatically write changes to XMP active in Catalog Settings? If yes, try disabling it.
What tools are you using when the spikes and lags occur?
Are you applying profiles for Lens Corrections?
thanks for reply. this is good news to hear.
regarding your questions:
Auto write XMP - already disabled
Lens Corrections - on occasion
tools used during lag/spikes: overall exposure, any tool in combination with adjustment brush.
for tools , there might be more, but i cant remember all of them right now.
I'm wondering if it has somethign to do with applying lens corrections. i stopped using them to see if lag/spikes decrease and so far so good. Is it possible that applying lens corrections would cause such spikes/lags?
The lens profiles require a fair amount of processing and have been known to cause some performance issues particularly when using adjustment brush or healing brush. Some folk have found it better to apply the lens corrections after all of the other edits have been completed. The engineers have confirmed that this is a valid workflow.
Hmm... This is interesting. I am quite impressed with LR3 performance on my two machines MOST of the time.
(Late 2007 20" iMac 2.4GHz C2D maxed out at 4gb and a Late-2009 15" MBPro 2.53 C2D w/4gb, soon to be 8gb as I just ordered the extra ram from OWC, a birthday gift to myself , they had a screaming deal and I can trade in my old sticks for $39).
The only hiccups I see on my systems are when I do a spot heal/clone on something bigger than a pimple. In this case I get beachballing (especially at 1:1 view) for about 10 seconds, and I have flashbacks to my previous software (not mentioning any names here, but it rhymes with "blaperture tree" ).
Auto lens corrections were applied to all the photos in my current project, I did that as an import preset thing because I thought that I would be using them anyway and it would save me forgetting to apply them.
With this new info, perhaps I should do as suggested and apply the lens corrections at the end of editing and see if that speeds up the spot healing tool. I guess applying lens corrections upon import isn't ideal?
FYI local adjustments (brushing etc) are all real-time, even at 1:1 view, and of course sharpening and NR are also real time even with lens corrections applied.
Thanks for the info.