I've just bought Hitman 2 on special and am running it through Gog Galaxy. It is running really slowly. The audio is fine, but the gameplay/cutscenes appear to be at somewhere about 50-60% of 'normal' speed.

Has anyone come across this/know how to deal with it? I'm running Windows 10 on an I7. It runs Witcher 3 at 60fps; can't imagine what would be causing H2 to slow down.

You did, of course, check this place? https://www.gog.com/support/hitman_2_silent_assassin

It sounds like a compatibility issue but I cannot be more specific.

The older Glacier engine games are very vulnerable to dynamic CPU clocking. If your CPU is set up to throttle up and down depending on workload the game simulation slows down or, more commonly, speeds up to ridiculously high speeds. It can be like watching a VHS-tape fast forward.

The only fix I can think of is to disable any kind of dynamic clocking features, most likely in BIOS. I have no experience with i7 processors and all BIOSes look different so I can't help you step by step. If this all sounds like technobabble to you I'm sorry, your only option is to pick up a manual or do some googling.

Be aware that you're not suffering a performance problem. The game probably renders a very high amount of frames per second. The problem is that the gameplay requires a fixed CPU speed/clock. I'm guessing the game checks how fast the processor is when you start the game up, but after that the CPU may clock down or up, meaning the game has the wrong idea of how fast it should play.

It's a D3d issue of some sort. Some of the new widescreen patches use a D3d 8 to 9 wrapper which should fix it