It’s likely because you updated QuickTime with the Tiger install and the Panther re-install wouldn’t undone that. Not knowing what your process for installing is, it’s tough to know for sure.
Did you do a complete wipe and install on a fresh drive? I have upgraded to Tiger in the past several weeks and have not noticed and “slowing”. If you just installed Tiger over Panther, that may have been the source of your slowing to begin with. Installing Panther back over Tiger could possibly create even more issues.
Again, I don’t know if this is what you did, but IF you did that, it may be worth it to backup what you have now and fully erase the drive and try your Tiger install again. Or if you just don’t trust it, install Panther again, but always install an OS upgrade on a clean drive. Updates are fine, but version upgrades are a whole different ball game.
debe