My mac is working little slow.

Usually that happens when third party programs are installed that run constantly from startup. There are a couple of categories of apps that are known to slow you computer down, they are:

• Cleaners
• Optimizers
• AntiVirus
• VPN

The best way to determine if you have programs running constantly at startup is by posting the free EtreCheck report using the Additional Text option when posting. The report contains no personal information, but is valuable in determining what is going on with your computer that would cause it to slow down.

How to use the Add Text Feature When Post… - Apple Community

What exactly do you mean by "It's working slow?" Updating alone may not be the cause.

To get a better idea, I suggest that you run an EtreCheck report, and optionally, post it here if you need assistance with interpreting its results. If you are not familiar with EtreCheck, it is a diagnostics app, developed by a valued forum member, that greatly aides in troubleshooting difficult Mac issues.

Ref: Using EtreCheck to Troubleshoot Potential Mac Issues

Could be, so update it: Update macOS on Mac - Apple Support