Libressl is openssl with a coat of paint (a sane interface) and improved documentation.
They are doing good solid work, but I would not expect any dramatic improvements in security and seeing as the openbsd project values correctness over speed, very likely a small hit in the speed department.
LibreSSL also has focused on removing code which is viewed as being actively bad (poor/problematic reimplementations of stdlib features), or less valuable or not aligned with OpenBSD's goals (ex: FIPS support).
It's probably worth benching just to see the impact of these changes - the fork happened around the same time as BoringSSL, which as these graphs show has quite different perf characteristics.
They are doing good solid work, but I would not expect any dramatic improvements in security and seeing as the openbsd project values correctness over speed, very likely a small hit in the speed department.