Ridiculously slow speeds on my new Nexus 5 too.
While browsing the web is as speedier than on my Gnexus, the Gnexus is able to download apps from the Play store a few hundred times faster than my Nexus 5.
Tried Factory resetting, tried clearing cache and data, tried the DHCP method above, nothing seems to help.
And to make it weirder, from time to time it reaches normal download speeds for a few seconds, sometimes up to a few tens of seconds, but then immediately returns back to the slow-poke speed.
There is one thing though, I ordered my N5 from America and am using it in the Netherlands (I expected only the LTE bands to differ, but I don't use those (GSM network here) so I figured I'd be fine) So could this be causing issues? I very much doubt it, seeing as wifi is wifi, but thought I'd through it out there just to be sure.
Another thing is that I haven't put my SIM card in it yet (wanted to swap the SIM after I fixed the Wifi issues) so could that cause some problems?
Really need to know if it is a faulty model or a software problem.
This issue has been pissing me off for the last couple months. I tthought it was my router (Asus RT-AC66U) so I factory reset it yesterday and still no improvement. The Speed Test app on all my GS3, Nexus 7 and Nexus 5 all show they can utilize my full bandwidth but yet YouTube and the Play Store perform so terribly. I am very stumped.