Hi Matty.
Thanks for uploading the full install of warlock. I've had a very quick look and there is an issue I've found that answers one of your main questions about speed and display.
You have (approx) 200+ individual png images, all of different unrelated sizes. This will cause any display to be slowed down, particularly on lesser cpus such as mobile.
You will need to learn about atlassing plus making sure all graphics are the best size for output.
It's about optimising load times, and GPU hit. GPU's want the least amount of textures and textures that (preferably) conform to hex sizes (definitely even size).
E.G.
Have just a few mega textures of 256x256, 512,256, 512x512 or 1024x1024, etc. And then fit all your graphics into these.
You will probably have to learn how your language accesses atlas textures and how to feed them into your sprite manager, but you will get a HUGE speed boost in display

It will also discipline you in how to prepare graphics for games and target sizes better

As an example, heres one of the sprite maps I used in one of my games:

Although it is very small, the concept remains the same: everything is packed into a single image giving virtually no overhead. if it was 200+ tiny little images the GPU would begin to have a fit - even though the images would be small. It's the number of thing not the size that counts

I've also had a look at the general scales of the sprites and a suggestion here would be the following:
Use a good sprite editor (whichever you feel really happy about) and use a sprite size of 64x64 pixels.
A single tile would be 2x2 sprites = 128x128 pixels for isometric which would fit the size you tend to use.
Here's an example of your sprite with a base template

the white being the base the height giving you room to draw, etc (ignore the slight variances in line width and stepping, that was just the app stretching things)