Compute-intensive packet processing (CIPP) in a computer system comprising a programmable computing platform is accelerated by using a packet I/O engine, implemented on the platform, to perform packet I/O functions, where the packet I/O engine is configured to achieve direct access to a network interface card (NIC) from a user application. For a Linux-based computer system, standard I/O mechanisms of Linux are bypassed and only the packet I/O engine is used in performing the I/O functions. Furthermore, the computer system is configured to: process a batch of packets, instead of packet by packet, in every function call; and when moving a packet between a buffer of an individual user application and a queue of the packet I/O engine, copy a packet descriptor of the packet instead the entire packet. In addition, workflows across different working threads are balanced and parallelism is exploited to fully utilize resources of the platform.