Poor performance under portrait mode

[ITAdmin]

Originally Posted by kingsapo

Hello. I recently bought a StarTech USB 3.0 Dual Head Graphics Adapter (with the DL 3900 chipset) for my mac. This adapter uses USB 3.0, and runs great under the standard configuration. However, I had intended to use it with a monitor that supports rotating to a portrait orientation. While the Mac's system preferences support rotating the video, it does so at a huge performance cost. Under landscape mode, everything is nice and smooth, and there is no noticeable lag at all. Under portrait, however, there is a huge amount of lag, from simple things like moving windows around to blocky and laggy screensavers.

I'm pretty sure this is a driver issue, since switching my other displays (which are using the built-in graphics) to portrait doesn't result in any of these issues.

I am running OS X 10.8.4 with the 2.0 version of the DisplayLink drivers. I have also included my system report, in case that is needed. Thank you for any help you can offer!

Just wanted to bump this and add my 2 cents. I'm experiencing the exact same problem. My older USB 2.0 adapters on a usb 2.0 hub performed much better in portrait mode than this adapter does connected via USB 3.0.

Same chipset, but in my case it's the Targus USB 3.0 Superspeed Dual Video Adapter (Model ACA039US).

I'll also note I run Windows under Parallels. The laggy performance is a bit noticable under Mac OS X, but when you add the additional performance hit of pushing video thru the VM layer into the Windows guest virtual machine in Parallels, it renders the rotated display virtually unusable. I disabled the rotation on the monitor to drive it in "standard" mode in OSX and the difference is stunning. Comparing 2.0 and 3.0 usb video solutions:

Using "standard" rotation: USB 2.0 was not bad at all. USB 3.0 is much improved - very very good!

Using "portrait" rotation (270 degrees): USB 2.0 was not bad at all. No performance hit for having the monitor rotated. USB 3.0 is much WORSE than USB 2.0 ever was.

A clear driver issue here that needs to be addressed.