No idea how to get the keyboard installed, without a keyboard, but i used xvkbd via apt-get to type @ since it is missing in my 3rd-level-less hwkbd layout.

On Performance, the Nexus 5 is roughly 4 times slower in storage access than the Pro¹.
Nexus 5 is 4.7Mb/sec read speed and Pro¹ whooping 18.73Mb/sec according to sysbench.
Jolla Phone was only 1.14Mb/sec.

Memory speed is only a bit faster on Pro¹:
Pro¹ 403.3 Mb/sec
Nexus 5 375.23 Mb/sec
Jolla 1 195.15 Mb/sec

Calculating prime numbers up to 2000 with two cores:
Pro¹ 3.77sec
Nexus 5 5sec
Jolla Phone 9sec

Now half that time for nexus 5 with quad core and 1/4 the time for Pro¹ with octacore should give a rough idea why xfce lags on Nexus 5.