Mediashakers ads really slow for UK?

Hello,
Ive been running mediashakers ads about a month now and at the start they were fine, Ive recently noticed they are making my site load extremly slow. When i check using a proxy they seem to load fast the proxy is located in US.
Is there any reason why the ads load so slow for me? They dont even load at all sometimes after waiting several minutes.

See original post by olli460