Garys Mod not working well on Mac or something. Please help

I was trying to play an online server with my friend, so I went to login and I went o download the files every server makes you do and it just pauses in the middle every time on every server I try so i manually install the files and lets me login, but its all glitchy, and laggy, the sound cuts off, and its nothing like I see of youtube videos of the server and I have like no features like /report and I can’t see name tags or use a gravity gun or anything… Super Glitchy and can you please fix this.

il break this down because you dont seem so bright

what kind of COMPUTER do you HAVE, WHAT PARTS are inside of the COMPUTER

I have an iMac OS X with a 3.06 GHz Intel Core i3 and 4 GB 1333 MHz RAM

[editline]18th June 2012[/editline]

And sorry about my first post. I was all pissed that this game won’t work correctly…

[editline]18th June 2012[/editline]

OK now when I start it up its not even going to the menu screen just not responding here saying loading

have you tried reinstalling