I've always had /boot on the OS partition but thinking of mounting ESP at /boot to use EFISTUB and boot directly into the kernel from UEFI. The ESP would be using FAT32 (obviously). vmlinuz-linux, microcode, intrd and it's fallback would be on that FAT32 partition.
Would there be any sort of performance impact simply because the kernel is on a FAT32 file system and not on something like EXT4/BTRFS/etc.? Or a slower boot time (since the initrd, microcode is on there)? Is it bad for encrypting a disk (where ESP is unencrypted, and OS partition is encrypted)? What are some other disadvantages of the ESP on /boot? I'm not dual booting with another OS, so that should be fine.