interrupt controler question

Using the old i8259 interrupts controller, my 1-way Linux2.4.16 box livelocks when receiving a high rate UDP flow (interrupt rate is so high that the NET_RX_SOFTIRQ never gets the chance to pull the packets off the backlog queue). However, the receive livelock phenomenom completely disappears when making use of the IO-APIC.

Anyone has an explanation for this?

THX.

Eric