Dell with Killer wireless has very slow Wifi (but my other devices don't)

I was having trouble with the AC-1535 in my (not quite so) new Dell XPS 15 and got a couple of answers from Killer support.

I sent them a Killer diagnostics report and he said the signal strength was low enough that it might be causing problems, and suggested I try the following steps to fix it:

Right click Start

• Right click Start
• Click “Power Options”
• Click “Change Plan Options” on currently selected power plan
• Click “Change Advanced Power Settings”
• Click “Wireless Adapter Settings”
• Under “Power Saving Mode” change “Setting” to “Maximum Performance” on both “On battery” and “Plugged in”.

Sure enough this has boosted my signal strength by >10% when on battery, and average packet loss has gone from >10% to <1%!

Just found this: https://superuser.com/a/311452/167358 - which is basically the same answer. Wish I'd clicked on the 'related questions' button before!