That's unless you're using a hardware wallet. (your post history hints you're using one or two)
The worst thing a malware can do in that setup is to change the copied bitcoin address.

In that case, the Portable binary on other's PC isn't much of an issue as long as you verify every detail in the transaction before signing it.
The connected Electrum is pretty much the same as a watch-only wallet and a malware cannot steal the keys in the HW.

You're still not safe "physically" though since you're using your wallet on others' PC.
Only use it on people/place that you trust.