After a big update before multiple days, it is taking more than 1 min to load the desktop even I have an SSD and before that update, it was loading it immediately. How this issue can be solved?
This was an issue in Loki. It's an issue related to the at-spi dbus. I have not experienced it in Juno, but what I would recommend is executing the following line:
sudo mv /etc/xdg/autostart/at-spi-dbus-bus.desktop /etc/xdg/autostart/at-spi-dbus-bus.disabled
I have a long list of "fixes/workaround" that could be applicable for many issues within elementary, affectionately known as eLC or the elementary OS Combobulator. Unfortunately I have not had a chance to test them all in Juno. But they might come in useful for you and others.