"An external entropy generator also provides more entropy, in terms of bytes per second, than the kernel gets simply from /dev/random. “Dev/random provides a few bytes per second,” he told Vulture South. “We provide about 64k bytes per second”."
This does sound like a great source of extra entropy, but there are non-blocking pseudogenerators considered secure as long as they are correctly seeded, so with proper operating systems, it's not simply a case of 'slow but good' / 'fast but suspect'.
Yarrow (the predecessor to Fortuna - https://www.schneier.com/fortuna.html ) gives 60MB a second on my modest server:
5:32 (3) "~" jamie@catflap% dd if=/dev/random bs=1m count=100 of=/tmp/fart
100+0 records in
100+0 records out
104857600 bytes transferred in 1.723317 secs (60846374 bytes/sec)