Thanks for the reply.
1.- Does the orange ball in the bottom toolbar for Avast have a symbol in it like a red "X" or a yellow triangle with an "!" in it?
No, it works properly.
2.- What else is starting up when your machine boots up besides Avast?
Only printer Epson and 2 programs for backup, I don´t like to have many applications at startup.
4.- Are you getting any other errors with Avast once it begins to work? Are your definitions up to date?
No, any errors. It works properly and I have the definitions up to date everyday.
5.- Did you upgrade or do a clean install of this build of Avast?
Yes, it´s updated to the last version.
6.- Did you have any other antivirus on your machine prior to Avast?
No, only Avast and Windows Defender.
7.- Do you have any other resident software running on your machine? Firewall, other scanners, etc.? More info. would help.
Well, the Windows Firewall but not any other software with the same utilities.
I´ve tried another test. I´ve started Windows in Safe mode and disabled the Avast Service and started again Windows. Now, the start was faster as before, no problem. I started again Windows and enabled Avast and the system is slow again, more than 4 minutes to start.
I was thinking on uninstall and install again Avast but I´m not sure it will fix the problem.
Thanks and regards.