According to MikroTik's specifications
https://mikrotik.com/product/rb4011igs_ ... estresults, RB4011 should handle 2016 Mbps with AES256+SHA256, but that is for 256 tunnels and packet size of 1400. It lists single tunnel performance of 1577 Mbps for different configuration (really, shouldn't matter that much as it's offloaded). However, the 512 bytes column is usually closer to what you get in real world. And it's listed as 578 Mbps, much closer to your results. Their tests are likely done with an empty configuration, no firewall etc.
In my limited experience with IPSec on MikroTik, it's usually bound by single-threaded network operations rather than encryption itself, which is hardware accelerated on most models. So a single tunnel performance is not leveraging the full hardware potential.
I know it's a different beast, but I'm sure WireGuard could push a lot more on RB4011 thanks to better multi-threading. WireGuard can work with FastTrack enabled, that helps a bit too. I could achieve over 300 Mbps iperf3 between two hAP ac2, which are at least 50% weaker than an RB4011.
RB5009 has a better CPU over RB4011 but same frequency, so it's not clear how much better it is in single-threaded operations. My guess something like CCR2004-16G-2S+ would be noticeably better at this, but I don't own it so can't say for sure.