libzip is used heavily during class loading when a jar is used. Currently it uses lseek and read when loading classes from the zip file. This incurs 2 system calls. The equivalent can be achieved using pread which is a single syscall on Linux.

Windows also allows you to do something similar by using OVERLAPPED with ReadFile. When used in synchronous mode, Windows will use OVERLAPPED.Offset as the offset to read from. This allows avoiding SetFilePosition, the equivalent of lseek.