Composer, the new dependency manager for PHP, works much better than PEAR for portably installing software with many dependencies.
I just ran into the fairly well-known problem where the Django Admin interface loads very slowly when you edit a record, that has a foreign key, to a big table (thousands of rows), because Django constructs thousands of objects to populate the dropdown lists. I tried out django-ajax-selects and it worked excellently to solve the problem and improve the user experience.
Antivirus software is always a contentious question. It seems that there are no right answers: nothing detects all viruses, and everything has an impact on the speed of the computers where it's installed. And there's a tradeoff between these two. My own subjective, biased choices are F-Secure, AVG at a push, and definitely not Kaspersky. Here's why, and some data to help you choose one for yourself.