EVM is an interpreter (of a EVM-compatible bytecode). With a bit of imagination, you could compare some of its features (such as the interpretation) to features of a Java Virtual Machine. It doesn't have a CPU that you could use to calculate the computing power.
Edit for clarification: Each EVM instance uses the computing power of its host.
To answer your question:
As every full node processes every transaction, does that mean that the EVM is constrained to the node with the smallest computer power?
I think you're imagining the EVM as some network-connected one supercomputer. But it's really not. The Ethereum network doesn't wait for the last currently active full node to validate the block. It's the other way around - if a validator finds an invalid transaction (using their local instance of EVM), they proactively broadcast this information.
So the simple answer is: No, the EVM is not constrained to the node with the smallest computer power.
Note: The original question before edit was asking about computing power in megaflop
One more small inaccuracy: Flops are based on floating-point numbers. EVM doesn't support floats, so from this angle, it's also impossible to calculate the computing power in flops.