TomatoUSB

Firmware: 1.28.9052 MIPSR2-beta23 K26 USB Ext

I just noticed that the CPU usage goes through the roof when I'm downloading @ max speed. I only have a 16Mbit PPPoE connection, nothing too fast. When I download off usenet, tomato's web interface goes to a crawl and CPU usage is above 1. I tried telnetting in and running top -d1 and I see that SIRQ is taking up ~90% of the CPU when downloading.

Any ideas what is causing this?

Edit: I just tried some speedtest sites and it doesn't matter what/where I download from, as long as my connection gets maxed out, the SIRQ usage goes above 80%

From wired or wireless client?

Wired client, wifi is turned off on the router.

I have similar with ranging from 75-to 98% on at 16M maxed out (deluge) though it tends to drop and hang around 6% for a while then later hang around 90s again, I tried disabling logging and no effect, also always at 100% when transferring to /mnt/usb from workstation via samba. This seems odd to me as to my recollection this didnt used to happen on my buffalo whr-300n running ddwrt.

oh and wireless is enabled but has no traffic on it

What build are you using?