Definitely use HTTPS in conjunction with TOR (if you're going to use it). Like that diagram shows, the exit nodes on Tor networks suffer from a vulnerability by design. That exit node may be able to dump RAM and see anything passing through it.
Also, props on obfsproxy. If you're that paranoid about NSA/ISP dumping your info, running obfsproxy should mitigate the DPI(Deep packet inspection) techniques these guys use to determine TOR protocols. That's not to say the math geeks in the NSA labs aren't already working out how to determine what TOR traffic has been obfuscated.
Regards to TOR being slow, if you look in TOR's connection info, you should be able to drop the bottleneck routers (i.e. the ones with low throughput)
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