HP Probook 450G2 notebook with Ubuntu 15.04 here (RTL8723BE wlan chip).
Default, fully updated kernel gives horrible throughput (about 600-800 KBytes/sec over FTP on same VLAN when just under the access point). It's very unstable as well, drops as close as 10m from the AP in direct view.
I've compiled and installed lwfinger's rtlwifi new driver from Github. This new source has significantly improved network throughput under very optimal conditions (right next to the access point). FTP transfers now over 1 MByte/s.
However in real-life conditions, performance still is very poor, signal drops to 1Mb/s speed only 20 meters away from AP in direct view (hospital corridor). Roaming between APs is slow and unstable as well and connection drops completely sometimes. Same notebook under Windows 7 gives very decent speed and connection stability in the same places. A whole world of difference... Any hopes for more improvement to come? are issues known and worked on or is it still quite shady at this time? I need to make a decision as to the deployment of these nootebooks and I'd hate having to push them out with Windows aboard (they're being used as thin clients for Citrix-published apps).
I can help in any possible way such as gathering debug output if this is needed.
EDIT : this is not a duplicate of "RTL8723be: poor and unstable wireless in Ubuntu (from 14.04 to 15.04)" as suggested. Well, it might actually be because using lwfinger's rtlwifi new driver precisely was the answer given there. However I've tried to comment there but my comment was deleted and I was asked to open my own issue instead. So here it is.