The multi-hops incurred by Tor increases the latency, but not necessarily the throughput. Tor is slow because there are too many users leeching from a small set of altruistic relays.
Tribler is better because every user becomes a relay. It is still constrained by exit nodes (not enabled but default), which is needed to talk with non-tribler clients, but that is not a problem if the majority of peers are using tribler, and traffic is mostly in-network.
About becoming a target, I have the same worry, but I don't think that was what happened with file-sharing with search features. The problem is that search was unreliable, full of malware and spam. I think that can be solved with a Sybil resistant reputation system (the hardest part of the problem).