Why is Blowfish so slow on router compared to AES?

[saffron]

Setup: RT-AC68U, latest Merlin, overclocked to 1200,800

Why is OpenVPN Blowfish (BF-CBC 128bit) so slow, approx 20mbps?

Compared to OpenVPN AES (AES128, AES256), approx 50mbps?

Is the router really that optimised for AES? The issue is definitely the cipher and not the connection/server.

Another on the PIA forums has found something similar with the same router.

 

[ryzhov_al]

Why is OpenVPN Blowfish (BF-CBC 128bit) so slow, approx 20mbps?

Compared to OpenVPN AES (AES128, AES256), approx 50mbps?

I don't know which cypher requires more calculations, but I know openssl got several assembler optimizations for AES/SHA. Here is an example of performance boost for one asm optimisation on MIPS CPUs.