No, I don't have that problem, but admittedly I don't have 408 friends - perhaps the best way would be more preferences; members could choose what shows up on their tracked activity respective to their individual needs and wants.
That is maybe too simplistic; this would mean more hours of design etc for the chess.com staff; we can't have preference on everything. But certain "tick box" options could very well suffice. Like you say, no harm in suggestion 
Well the wish for it is there, sometimes i try to find something back but it is then impossible. Maybe a search option on a word or phrase out of the topic title, or the option 'all topics from one specific person' with it could help also if the suggestion of Kacparov would be implicated.
http://www.chess.com/members/view_content/Kacparov
All my activity is there because there are 8 pages. It would be nice if friends activity would also show up like this, with many pages.
Well the wish for it is there, sometimes i try to find something back but it is then impossible. Maybe a search option on a word or phrase out of the topic title, or the option 'all topics from one specific person' with it could help also if the suggestion of Kacparov would be implicated.
These would both be nice. In the meantime, Google search provides a powerful alternative.
I would like to see that also
I don't really have that problem that much because you're the only person I track.
Sounds like a good idea to me. The user should be able to set all the numbers... I'd like to see the recent posts in the forums increased too.
You can already see 100 pages (about 2000 items) of the most recently created threads - albeit not the most recent posts.
In the current "My Tracked Activity" (friend activity) tab, you can only 20 latest posts. With the amount of friends I have (408), if I leave for more than 1 day, I can't see all the posts. It would be nice if this list would show more, maybe even all activity. It's just a suggestion, but it would be nice to see if anyone else has the same problem