i have also had performance issue at close to the 1000 population mark, also on a mobile platform but my spec is i7-6700HQ 16 gb ram Nvidia geforce 950m, its an msi apache pro gaming laptop, and most stuff I chuck at it has no issues, by the loks of it it could be due to the 950m as the comment above seem to be using a similar graphics card. Have no issues with full screen etc.