Why is asymmetric encryption ~1000x slower than symmetric?

Because it relies on computationally expensive mathematical operations — modular exponentiation on huge numbers — rather than the simple bit operations of symmetric ciphers.

Why it's slow:

• Symmetric crypto (AES): Simple bit operations (XOR, substitution, permutation)
• Asymmetric crypto (RSA): Modular exponentiation with very large numbers (2048+ bits)
• The mathematical hardness (factoring, discrete log) that provides security also makes computation expensive

This speed difference is why we use hybrid encryption in practice — asymmetric crypto for key exchange, symmetric crypto for bulk data.

Go deeper:

• RSA (cryptosystem) — the modular-exponentiation cost behind the slowdown.