Yes if your laptop is a older model it may not be coping aswell with TT as others can.
Also having a bit of space on hardrive always helps, at least 3gig of space is recommended to help performance on most 3d games. Even windows recommends that for file swapping for uninterupted performance.
For sucessful TT Play is :-
Recommended:- Pentium 4, 3.6, or amd equivelant or better, 1gig of ram+, 128 grahics or more, 5+ gig of drive space for file swapping.
Minimum:- Pentium 4 or amd equivelant, 500meg ram, 64 meg graphics, 3gig of hd space for swapping.
Of course above specs are a very rough guide, and having more of one can mean you can get away with less of another.
Also check machine for spyware/virus and use HD utilities to clear out tempory internet files and compress old files etc. to create more space, and check to see if HD needs defragging (cleaning up and maintanance is always good idea especially if space is a premium)
Also your connection is another important factor, modem users will have more problems, but even if your broadband and use wireless router to connect your laptop to internet, then this can affect the way TT plays.
Check this port triggering thread for help on setting router port settings as it may just be that.
Thread for fixing broken connections
All above may help you to stabilise things and all not that complicated to do, if you put your mind to it
As far as buying CD making difference to way game plays. No is definetely the answer to that, whether you download from site or buy in CD form its the same.
'Keep it Kool :Cool:'