I've just spent 2 days working on why my first level in "A tall story" was lagging horribly, entities nodding like they needed some medical care, then I noticed a couple of models missing and a trigger I replaced these and rebuilt, my fps went from 5 to 50 all the ai on the map started to do what it should...amazing how such a little thing can make a difference. So I would say check your maps if you have these issues as it seems that sometimes there's an easy cure this is a big map with 100's of lights and lots of entities and mines an older machine but now plays like a new game

I've seen this, I spent hours removing items and such, changing settings to get speed back. Then I loaded in an older map, but not really much different to the one I had been tweaking. It ran fine. Something had caused a huge loss of frame rate in the old map. Even after removing many item's and having a lot less populated map it ran badly. The old one had more stuff and ran back at 60 fps which was my original goal, rather than the 30 odd it had dropped down to.

It's a weird one, but definitely can happen, and can kill your map if you don't have a backup or notice a difference as in the above post. I think it is a bug, a really nasty bug, but difficult to notice. I imagine a few people have encountered it but simply put it down to GG being slow. Something seems to hog resources badly when it happens, even dropping down to lowest shaders didn't help much for me at the time.

Ive since been suffering with this again and used F11 to try to track it down, nothing seems to change much but then i noticed im using DX 12 so im wondering if this could cause the issue as GG uses DX9.

If you use F11 and deactivate most of the features, you will notice a huge change (no terrain, no entities) DX12 should not have any effect on the DX9 engine used by GameGuru. You can use F11 to switch off one item at a time to work out which one is the culprit for greater than normal slow down.

Thanks Lee F11 dind't really show me the problem (no idea why) but i turned off the grass and it shot up to over 36 fps from 1-5 :/ i presume its my graphics card only 1 gb so its fine i've placed lots of non animated plants which doesn't seem to effect it and still gives a nice effect

It's a tricky part of game engine development. Spend time making existing rendering faster, or add new features to make rendering look better (and in the processing adding more performance hit). Hopefully GameGuru strikes a balance between the two.