I received an inquiry for a client that they had decided to move forward with USB based external touch screen monitors in their environment. Everything worked well in their test environment but as they rolled out, performance became a problem. But why?
Reason #1 – DisplayLink uses CPU cycles
Unlike a normal monitor like a VGA, DVI or HDMI monitor, monitors (including touch screens) that plug in via USB are likely using DisplayLink or a similar technology. These rely on a software driver that tries to use the graphics card in your computer but when it can’t, it us using CPU cycles to create a virtual video port. Fast action video will be slow and choppy at times and quickly moving your mouse or a window may even exhibit some stutter, even on the best of PCs.
Reason #2 – USB 2.0 is not fast enough. USB 3.0 has been out for a long time now but like with many large companies, branches and smaller officers may not have the latest computers. USB 2.0 is particularly a problem for newer DisplayLink tablets and monitors because the greater the pixels, the more data that needs to transfer.
In the end, perhaps the client should have looked at upgrading computers with their project or chose to use a tablet PC instead of a external monitor. As the client evaluates options, their from their experience that older PCs and USB Displays are a bad combination.