Touchpad lag after doing last update

hello forum ppl. I have netrunner rolling installed on 3 laptops, 2 of them are fine after the update back but on my oldest one (intel core2duo 6gb ram) i now have a serious lag on my touch screen, it works fine on the login screen but once you are logged into the desktop the lag begins. The only thing different on this laptop is that it was installed originally from the 04.2014 iso and the other two laptops were done from the lastest iso back in september, the only thing i did different was i noticed on the latest iso they added the krunner feature on the taskbar and i couldnt find it on this computer so i searched for it in the package manager and i installed a package called krunner, it had to remove a package in order to install, i did this a few days before the update but i never rebooted the computer until after the update and now i have a serious lag on the touchscreen. Any ideas or suggestions? is there a way to a fresh install/reinstall without wiping the hdd? any feedback would be appreciated, thanks

OK, remove the krunner package and all the other KF5 packages that it pulled in with it, these are intended for use with Plasma 5 (KDE-Next).

krunner was already installed as part of the kdebase-workspace package for the KDE SC 4.xx series desktop environment.

To answer your other question, unless you installed your system using a separate home partition, NO.
You will need to backup your personal data and re-install, you could also install and use deja-dup, to make a backup of your home directory,etc. and restore it after you re-install as well.