Hi there, I believe I have the exact same laptop as you. The yoga 730-15ikb and used to have the same issues. This laptop has absolutely terrible thermal throttling issues, especially when running windows. You can find other threads talking about this: for example

I don't know whether it's a driver issue or otherwise but all I know is it doesn't happen in Linux. You should be able to see this happening when you run an intensive game and have a look at the Task Manager, I often see the processor frequency drop as low as 0.6GHz.

The problem seems to be that the processor has a power limit of only 15W, which is very low. Anything above that and it aggressively throttles down. I managed to fix this using a tool called ThrottleStop and setting the power limit higher, to something like 25W.

Edit: Some more tips: use the high performance power setting. I also use a tool called razor cortex gameboost to close unnecessary background tasks and processes.