[AVFS] Speed suddenly decreases after copying 100 MB of data

I mounted a http direct url, which points to a rar file, to decompress
it without downloading. I measured the read speed with utility "pv",
which in fact is a filter and shows a progress indicator:
 cat file.rar| pv |cat > file_copy.rar
 Initial read speed is the usual 10 MB / sec, but always after reading
100 MB of data the read speed suddenly decreases to a few KB / sec.
 Error log generated by option "-o debug":
http://pastebin.com/W3Z6TMrY

I am using Arch Linux (3.14.52-1-lts)

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