Hello Jyothi, welcome to the Microsoft community, I'll be happy to help you today;
I understand that after an update Windows 11 is starting slowly;
Initially I recommend that you do a disk cleanup;
Press Windows key + R and type: cleanmgr press Enter;
Click on Clean system files and wait for the files to load;
Select all files and click OK to delete them;
Enable fast boot;
Access the Control Panel and click on System and Security;
Click on Power Options;
Click on Choose what the power buttons do in the menu on the left;
Click Change settings not currently available;
Check the option "Turn on fast startup (Recommended)";
Click Save Changes;
Restart the PC and check if the startup is still slow;
Hope this helps, see you soon!