Any tips for tuning NetBSD for NAT?

[Dave Huang <khym%azeotrope.org@localhost>]

Hi, I have a Soekris net5501 (AMD Geode LX 433MHz, VIA VT6105M Rhine
III ethernet) running NetBSD-current from June 2015 and pf as a NAT
box. I just upgraded my internet speed to 100Mbps down/10Mbps up, and
it seems that the net5501 is a bottleneck. When downloading a large
file, I'm getting about 70Mbps, and "systat vm" shows that 99%+ of the
CPU is processing interrupts (and user processes are very sluggish
too).

Is there anything I can tune to reduce the CPU load (switch to npf?
tune sysctls?), or is the hardware just not up to NATting 100Mbps?
-- 
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