Slow laptop after clean install

In my opinion, and its only an opinion, restoring from recovery partitions isn't a good idea. In my experience, when you restore from a recovery partition you often times are carrying over any issues that you had on the computer from before. These aren't limited to virus/malware and other software issues.

A clean install is actually installing from a disc. Your particular Dell probably came with a recovery disc I bet. Maybe check around for it. If you dont have it, call dell and try to order it from them. If they don't have it look up a third party website to place your order for the recovery disks. http/www.recovery-disks.com/dell-xps-15-l502x.html is the disc set for your computer

In regards to using a 90w vs a 130watt, check to make sure that the output voltage is the same on both adapters. If it is different, then do not use it. If the output voltage is the same, then you can use it, but keep in mind that it will not function the same. It wont provide enough power for that laptop to charge and be used at the same time. Especially under strenuous tasks. Dell XPS 15 L502x Recovery disk should wipe that computer back to factory and allow you to clean up the partitions in the computer. This way you can be sure you're not carrying over any possible malware or software issues within windows.

Let us know what you would like to do! We can help either way. I would also suggest getting your heavier wattage adapter back up and running asap.