DirectInput8 EnumDevices sometimes painfully slow

Question

Sometimes (in about 50% of runs), EnumDevices takes 5-10 seconds to return. Normally it is almost instant. I couldn\'t find any other reports of this kind of behaviour.

Answer 1

As DaFox has pointed out, a likely cause appears to be certain device drivers being enabled. I contacted JDS Labs support (who sell one device which happens to install one such driver) and they kindly pointed out that the root cause is actually a bug within Windows (not the installed driver), and they actually provide the solution on their troubleshooting page. See Games hang or experience loading delays, which explicitly mentions VID_262. Disabling this driver fixes the issue without apparent side effects (under the condition that that is the only driver triggering the bug). As for what exactly is going wrong within Windows, here there be dragons.

So I guess the go-to solution (for users) is to scrape all the troubleshooting and FAQ pages for all devices which you have ever connected to your system and see if there is a mention of delays/lag caused by a driver.

As a software developer, you will probably want to benchmark the execution time of the affected code and kindly tell the user there is something wrong with their system configuration and where to look for how to fix it in case it is unreasonably long.