As we do so much more via the Internet this is now a frequent complaint. There are lots of reasons for slow Internet browsing, but the good news is some can be easy to sort.
There are lots of browser programs available. There used to be a big difference in browser performance, but recently performance in the main five (Google Chrome, Microsoft Internet Explorer, Mozilla Firefox, Apple Safari and Opera) has improved. See the links below for technical reviews and tests. The bulk of the browsing experience involves HTML and here Google Chrome and Opera are the leaders. Opera is also the leader for games and interactive websites.
Be aware that speed should not be your only criteria.