Ever since TeamViewer 13 was released with the new interface, I've noticed a MUCH slower connection set-up time.
In the old interface it takes <4 seconds to show the remote screen:
While in the new interface it takes more than 10 seconds to show the remote screen:
Also notice the weird flickering in the new interface.
This is on a Dell XPS 15 9950 with the following specs:
I've seen this weird behavior ever since TeamViewer 13 was released (and on Windows 10 1709, 1803 and 1809), hoping it would eventually be fixed, but the performance is still is bad. Even in the TeamViewer 14 preview.
Latest BIOS/Display drivers are installed, and I'm not having this problem in any other applications.
For now, I just keep using the old interface as it's more than 2x faster than the new one.