since the software is not "installed" until needed and is only "installed" to memory, the speed of your processor and the amount of memory is going to affect performance. (actually, before it is "installed" to memory, it has to be uncompressed thereby adding even more time.) what speed processor, how much ram and how much graphics power are you running?
but, yes; it will run faster if it is installed to disk.
i've been running ubuntu since breezy. i have dapper running on two drives and gutsy running on this one. i tried the latest, hardy heron, but came to refer to it as hardy heroin before i backed down to gutsy ... and am seriously considering backing down to dapper. (actually, i've been running a variant of "pc-unix" since 95 or so - freebsd up until version 5.)
i've found it to be an "acceptable" alternative, but keep getting the feeling that the "open source"/unix philosophy has gotten somewhat mangled in the push to be "just as good as windows" (sort of like being just as good as white folks). with regard to the aforementioned "philosophy", bear in mind that i am from the old school that knows that there is no such thing as an 4x4 with an automatic transmission.
one of the nicest things i've found is in the area of security; i've not had to run "malware protection", although there are suitable tools available.
but the best thing is that linux
requires one to set up user accounts which are so very much more robust than the johnny-come-lately nature of windows user accounts. (with xp, one can jump into safe mode and use that administrative account to adjust the properties of other accounts on the system. granted, if one wipes out the passwords for other accounts, one loses the ability to access the password protected data ... or so it says; i've never tried to access any of it.) without a password protected user account, one can't even log on! well, one actually could get to a root shell, but one has to know enough to mount the various partitions on the disk that have data in them ... provided one knows what partitions are available and which ones one would want to access. <grin>
it all works great as long as one is willing to forgo the "pleasure" of running some of the newer games. (even those work with the various windows emulators ... provided one's puter is fast enough.) there may be other "quirks", but i've been using open source for so long i've adjusted to whatever "limitations" that might exist.
some things are even easier than with windows, notably usb support, since one usually doesn't need to install drivers first. (although i'll have to acknowledge that i haven't run vista - it might just recognize some of the devices that i've had to find drivers for with xp or 9x.) more of the cameras i've tried with ubuntu "just work" without any problems or additional software.
on the other hand, one will have to do a bit of work to get multimedia playback as most of the formats are proprietary and can't be shipped with the default installation (mp3s and windows media formats). however, there are multimedia formats that will just work where they require a bit of extra work in windows (divx, ogg, flac). one can either hunt down and install the various media codecs by hand, or one can look into "medibuntu" with will help to install things like the multimedia codecs (including the windows media stuff!), acrobat reader, java, flash and a few other things.
bear in mind that i am running a 600MHz celeron with under 512 meg of ram on an i810 chipset. but just sometimes, i feel like i wanna back down to 9x so i can run some of my old favorite games like doom (se, 2 and final - i absolutely can not run doom 3 with it's heavier graphics requirements) and diablo 1 and 2. i've not done any of the online games. (i have never much liked the nt file system so prefer not to run xp and have never played with nt or 2k.) while i could dual-boot, i'll usually dedicate a drive to each one since i have a few very small (8, 10, 15, 20 gig) drives around.
dual booting is always an option if one wants to play with an alternative while maintaining a "safety net" ... but again, a bit of work is needed. (for a fresh dual-boot scenario on a newly formatted drive, be sure to install windows first as windows will overwrite the master boot record where linux will recognize that there is already something there and set up a boot menu.)
dang! i guess i could have just said "yes, it'll be faster, and yes, i run ubuntu", eh?