No
The hash is calculated only once (at most) - while the scanning may happen many times subsequently (and, since the files are bigger, the scanning may also take longer).
So, even though it’s a simplification, you might say - the bigger the file, the more benefit the persistent cache may bring for it.
(Btw, what makes you think reading the header is enough to find the malware? It’s certainly not…)
for example photoshop cs5 is 34mb and avast 6 resident shield with pesistent cache is more slow then avira
i guess because avast calculates the hashes of 34mb and comapre with its database
(Btw, what makes you think reading the header is enough to find the malware? It's certainly not...)
the virii almost every time ,to spread, they write themselves in the beginning of the exe