Recently I've noticed that the first time I run MBAM after booting up it tends to take a while to scan, and somtimes becomes unresponsive for periods of several seconds at a time. However, if I immediatley re-scan the scan is MUCH faster and it doesn't seem to hang like it does the first time. It has never crashed or permanently frozen, it just acts a little slow the first time.

For example, I just scanned three times in a row under similar conditions (1st one is the first time I've run it since reboot (minimal programs open, only AVG, Comodo, windows live messenger and Steam in systray), 2nd one is straight afterwards under the same conditions, and the third one is straight after the second one but while browsing the net with IE on top of everything the other tests had open.

The times were 3 minutes 52, 1 minute exactly and 1 minute 3 seconds respectively.

Any reason why the first run takes so much longer, and does this happen on everyone else's machines? (vista 32 here, running a limited user with MBAM 1.36 set to run as admin)

I probably has a lot to do with Superfetch getting everything cached into memory after boot. It could also have to do with all the system services that execute initially at boot that eventually self terminate once their startup work is complete. That would increase the initial resource usage as well as the number of processes MBAM would need to scan. To test, reboot again, wait 5 minutes without doing anything, then start MBAM, but it would also be a good idea to execute the following command from an administrative command prompt and then reboot before you do since Vista will be sitting idle for those 5 minutes and it tends to want to do these tasks the second there's no application demanding resources:

Well, I'd been using the computer for oh, I dunno, half an hour or so before I tried those scans. Have you run a MBAM scan since you last booted? I'd be interested in the times you get on two scans, one after the other (I know it's not a real comparison because of all the crap going on in the background, but interesting nonetheless)

What exactly does that code do?

Well I'm at work right now (on XP) so I can't test it at the moment, but I'll do so when I get home later (and I can do it without all my security software running because none of it runs at boot and my NIC is disabled at boot as well ). As far as that command, it tells Windows (yes, it works on XP as well) to process all of the scheduled "idle" tasks that need to be processed such as file indexing, background defragging, boot time defragging (a very nice one for boot times) and other such things. I do it at least once every month or so (especially on Vista) and it can make a noticeable difference in overall system performance and responsiveness, just keep in mind that once it starts you need to sit back and let it do its thing because it processes those tasks with full priority, not "idle" or "background" priority like it normally would so doing other things while it's running would really drain performance. When it's finished it will automatically close the command prompt window.

So it's just a one-off 'Get everything done' command to windows, and doesn't actually change anything? Good info to know.

I just did another little test on an admin account (as it does not load windows live messenger and steam on startup like my user does), gave it 5 minutes so that Vista could finish with the hard-drive thrashing it does at startup and ran two scans. Came out to be 3:26 for the first scan with 88254 objects scanned, and the second scan came out to 1:00 again (it seems to love that number on it's second scan lol) with 88259 objects scanned.

I might try uninstalling and reinstalling MBAM just to see if it does anything, as it's such a tiny download and quick install anyway. Should be interesting.

It could also have to do with the initial step of "Expanding registry prior to scanning" step that it takes at the beginning. Perhaps it's quicker once it's done it once.

Perhaps... that step doesn't seem to take all that long though. It's just slower overall. Then again, many programs are better the second time you run them, maybe it has to do with it all loading into ram and doing what it needs to do to scan. I'll test my fresh install now and post results.

EDIT: First scan (after letting Vista settle down after boot): 3:11

Second (with IE open for a short time when scanning) 1:02

Third (same conditions as first) 1:01

It's a bit quicker after a reinstall, but I can't really attribute such a small change to that. I'd be interested in the reasons the developers give for this increase in speed between scans. The varience in times isn't a problem, but I still wonder what causes it.

Of course, since you're on Vista, it could have to do with Superfetch itself optimizing MBAM by preloading its process into memory. I've had it happen after exiting a game and then starting it again, and man it makes a huge difference. I want a system with 20TB of ram so Vista can preload EVERYTHING into memory ! Even my old games load faster in Vista than they did in XP because of Superfetch.

Heh... that'll be the day. Screw hard drives, we'll have 100TB SSD drives (Lol, RAS Syndrome), with 1000TB extra for redundancy. Oh and several TBs of RAM.