Slow Startup in High Sierra

As it states "This machine has multiple antivirus apps installed." Uninstall "Sophos" and "Symantec" in strict accordance with their instructions. Repeat for "Cocktail". Other similarly ill-conceived junk may also be present, such as "Safenet". I am not familiar with it.

Rule 1 of Macs is don't install junk. Excerpted from Effective defenses against malware and other threats:

• Never install any product that claims to "clean up", "speed up", "optimize", "boost" or "accelerate" your Mac; to "wash" it, "tune" it, or to make it "shiny". Those claims are absurd.
  • Such products are very aggressively marketed. They are all scams.
  • They generally operate on the flawed premise that a Mac accumulates "junk" that needs to be routinely "cleaned out" for optimum performance.
  • Trial versions of those programs are successful because they provide the instant gratification of greater free disk space.
  • That increased space is the result of irreversible destruction of files, programs, or operating system components normally protected from inadvertent alteration or deletion. The eventual result will be unreliable operation, poor performance and random crashes that may not become evident for months or even years after their use, when updates to programs or macOS are eventually released.
  • Memory "cleaners" that circumvent macOS's memory management algorithms work by purging inactive memory contents to mass storage, which can only result in degraded performance and accelerated hardware failure.

There may be some items loading before login or there may be a different issue. Please download and run Etrecheck  It is a diagnostic tool that's very useful to us in finding problems. Also it will give us further specs on your Mac. After it runs post the log file here. It will contain no personal information.

To post the log file copy & paste it using the Page icon in your reply window:

A very long time ago "Cocktail" and things like it arose to address needs omitted from OS X, but it's been about fifteen years since then. macOS does all of its internal housekeeping automatically and has been for many versions.

I don't know what your needs for it may be, but whatever they are can be more safely and easily accomplished using your Mac's own built-in tools. And, as I alluded to, anything that seeks to "clean" memory can only degrade a Mac's performance. I'm not suggesting that's what you're doing with it though.

Another thought that I did not express earlier: there is no need to routinely restart a Mac, so startup times themselves ought not to be a major concern. I have Macs in my organizations that don't get restarted for months. They work best that way. Having said that, several minutes is not normal.

No, but a lot depends on the Mac, so describe which one of its many models you are using.

If you want to avoid having to answer many such follow-up questions one at a time over the course of several days, consider https://etrecheck.com. Its developer designed it specifically for users of this site, it doesn't alter anything without your consent, and can just be dragged to the Trash when you're finished with it.

No Anti-Virus software or so-called “cleaning” apps are needed or recommended for Mac OS. They can conflict with Mac's own built-in security. At best they will slow your Mac by using unnecessary resources and at worst will bork your entire system.

Uninstall Sophos, Symantec and Cocktail as per the developer's instructions.

If you want to post its report here, you have to use the "text" icon as macjack explained.