Its just probably the map itself as I still remember times where server made me have some frame drops but only once or twice and my only other thought would probably be the fact you do not have a dedicated Graphics card and your integrated Graphics Card is finding it hard, my only thought might not be the best help but I don't much other from others.

I am not 100% correct so this is only my point of view I could be totally incorrect.

Its just probably the map itself as I still remember times where server made me have some frame drops but only once or twice and my only other thought would probably be the fact you do not have a dedicated Graphics card and your integrated Graphics Card is finding it hard, my only thought might not be the best help but I don't much other from others. I am not 100% correct so this is only my point of view I could be totally incorrect.