And here is an experimental patch which enables the "priority requests" mechanism which was in the original new GIL patch. "Experimental" because it only enables them on a couple of socket methods (enough to affect the benchmarks).

Here are the UDP benchmark results (with 2 background threads):
* 2.x trunk (old GIL):
11.379 seconds (921515.168 bytes/sec)
* vanilla py3k (new GIL):
27.400 seconds (382689.529 bytes/sec)
* patched py3k (new GIL + priority requests):
1.828 seconds (5737130.676 bytes/sec)

And here's patched py3k with 8 background threads:
3.058 seconds (3429136.193 bytes/sec)

(benchmarks run on a 8-core Linux machine)