Bitswap client CPU hotspots

[hannahhoward]

Goals

Under heavy load, we're seeing high CPU usage in Lassie originating in Bitswap. Looks like a couple functions are pretty heavy CPU consumers:

• SessionInterestManager.RemoveSession
• MessageQueue.ExtractOutgoingMessage (and Wantlist.Entries within it)
  This pushes us towards 700%+ CPU usage on a Saturn node that affects overall performance.

Pprof visualization:

Source data:
cpu.pprof.zip
Lassie binaries (this is from the x86_64 build we think):
https://github.com/filecoin-project/lassie/releases/tag/v0.9.2

I suspect these hotspots are pretty common to heavy bitswap client usage and are worth optimizing.

[BigLep]

Obviously not good to have these hotspots. Unless these are blocking anyone right now, I'm not planning for us to do them as part of the current Kubo/Boxo "0.21 iteration" given the other tasks we already have assigned. I am noting it for larger "bitswap overhaul" work that we want to sink into later in the year.