Boot time will be minimally faster, as UEFI boot settings require GPT partitions and UEFI boot times tend to be somewhat faster than Legacy configurations.
Aside from support for larger drives without multiple partitions, there is also support for other TYPES of partitions, more than four partitions per drive and configuring your system for EFI settings allows other UEFI compatible hardware to be more quickly recognized and initialized which further reduces boot times.