You too, huh?
Last employer moved to McAfee "because active malware protection". Basically, AMP is a set of rules you can apply to disk accesses per application -- like for instance, "no application can delete PDF files from My Documents" (this is one of the "anti ransomware" rules).
It wasn't too bad with just the signature-based virus scan, but the updater and AMP were horrendous. The PCs (3.6GHz 8-core Xeon workstation with SSD, 16GB+ RAM and a ludicrously powerful 3D card) went from booting in 30 seconds to taking 15 minutes to boot. Eclipse took another five to start. When AMP was deployed to the JIRA server, JIRA refused to start (Atlassian Support suggested AV exceptions which IT refused).
IT response: close out any AV related ticket with "You will not be receiving a hardware upgrade and the AV is mandatory."
Six weeks later, IT was outsourced and the response became "we don't have permission to change AV settings" (BigCo politics).
Four more weeks later and the electronics lab was crippled as Labview got detected as malware by AMP.
A fortnight after, half the technical team handed their notice in.
It wasn't the only reason this FTSE100 was constantly outrun by its competitors, but it was certainly a contributing factor.