The new 1.5 version feels slower than the previous 1.4 version.
The durations of second start (with system cache):
V1.4 - 21s
V1.5 - 33s

Like you can see, something take longer at the end of the start. This must be the problem. (I hope the screenshot will not be deleted from message)
Another actions like expanding of the tree feels longer to, but I did not analyzed this yet.
pgAdmin 4 v1.5
Desktop Runtime
Windows 10 x64 1511
CPU: 3,5GHz
RAM: 32GB
HDD: SSD RAID 1