GPU spikes in profiler - used to be 100fps, now 30fps?

I have a question - I’m currently making a game and I’m getting pretty consistent spikes in the GPU according to the profiler. Now when I’ve opened the level previously, it used to average around 100fps without these spikes. I haven’t changed anything in the level since then but when I restart the editor, I get these GPU spikes and it’s killing my performance.

I’ve tried running it in both DX9 and DX11, enabling/disabling vsync, running it with “High performance NVIDIA processor” and tinkering with the resolution/AA/shadows… nothing has worked so far. No errors in the console either.

Does anyone have any ideas? I’m running a pretty high spec machine.

i7-4710HQ Quad core
nVidia GTX 850M

Any help will be very much appreciated!

Just a bit of extra info, even when there are no objects in front of the main camera (just terrain and my character model), it still averages 30 fps … the main cause of the performance drop is “Gfx.WaitForPresent” - I’ve investigated this issue before using the search but haven’t found a solution - I believe Gfx.WaitForPresent is the issue here but I still don’t know how to fix this.