High CPU usage in RarityMap.recalculate and BitField.get

[feross]

This happened when adding two Ubuntu ISO files in WebTorrent Desktop.

[FinnFrotscher]

Yes. +1
When I run webtorrent inside electron, it takes about 10 minutes until my mac is completely overwhelmed with a cpu load of 100% and it is only after I kill the electron and chrome processes that it drops down to normal (5%). Running the same electron without webtorrent the overload doesnt happen.

[feross]

@FinnFrotscher The issue you're describing sounds like #551 which is fixed by updating to the latest version of Electron. This issue was fixed in Chrome 51 and Electron 1.2.0. Make sure you're on that version, for both your local and global installation of Electron.

[feross]

I think this is causing download speeds to jump. My guess is that we're downloading too fast for WebTorrent to handle processing the data (we're doing something inefficient somewhere). This spikes the CPU to 100% during which time we're blocked and not acknowledging data from peers, so they lower their speeds.