I have laptop with Intel HD5500 integrated graphics card and also struggled with stuttering, which was for some reason more common during 2nd half. Using dgVodoo fix provided on Firebird patch page didn't work. Using D3DOverrider didn't work. Disabling fullscreen optimization did help a bit.
After trying all of that I installed dx8 to dx9 wrapper from this link http://enbdev.com/convertor_dx8_dx9_v0036.htm. Stuttering was gone, but there was some screen tearing. So, instead of using D3DOverrider I went to my graphics properties (you access this by right clicking on desktop), clicked on 3d tab and found an option to force vsync on integrated cards. There are two options: applications setting and driver settings. Pick driver settings. (This might be a bit different if you have different card) The game works flawlessly now.
Hope this helps you with integrated cards.
I've tried everything but nothing works, I've used the dx9 convertor, set the compatibility to XP/W7 and run the exe as admin, set high priority in task manager, change the exe of the game and a lot more of things but it still running bad even when the game runs at 60 fps all the time.
As I said I don't have a very good pc but it should be capable of run the game without problems, something weird is that the game runs exactly the same even at low/high graphics or with low detail in lod mixer.
If I play the game "normal", I mean without any dx converter it looks good, no tearing or anything like that but the input lag is just terrible and if I run it with the dx wrapper the game looks terrible with a massive tearing that I can't solve even forcing Vsync in Nvidia settings and it just improve a little bit the input lag.
The only thing that worked was updating my kitserver, I was using a very old version that didn't let me set the resolution in kload so I updated to 6.8.2 and when I put my resolution in the kload settings the game runs and look great but sadly for just one day and the next one the game started to run bad again so I don't know what more to do...