Ugh terrible, I've come across this myself with friends and some old family relatives I caught up with but no where near as bad haha!
This happens because one is ignorant/clueless and clicks Next > Next > Next as fast as possible when installing software therefor any bundled toolbar offers or 'crapware' gets installed along with the software you want install.
I myself have never liked toolbars even back in the early days, They slowed down browsing and browser start up times, tab loading times etc so it makes sense why her Internet has crawled to a slow.
Thanks.