Infinite Jest doesn't even crack the top 20 longest novels written in the Latin or Cyrillic alphabets, according to Wikipedia, and that list doesn't even include such ideogrammatic classics as Tokugawa Ieyasu's Sohachi Yamaoka , with 40 volumes and more than 10 million Japanese characters.
Judged in the loosest manner - sheer number of words, published in any number of volumes over any span of time - the list of longest novels is dominated by dreck, much of it self-published. The latest contender is the 17-million-word Marienbad My Love , an electronic novel described as a "non-linear literary collage" by Texas author Mark Leach, who boasts that it also contains the longest English sentence, at three million words. Scientology founder L. Ron Hubbard is a perpetual contender in such lists: Although published serially in 10 volumes, his 1.2-million-word Mission Earth is considered by some to be a single novel - and thus the longest in the English language.
Stripped down to titles still in print and generally available, the list of the 10 longest novels available in English looks like this, according to Amazon.com:
1. In Search of Lost Time by Marcel Proust. Approximately 4,800 pages
2. Mission Earth by L. Ron Hubbard. Approximately 4,000 pages
3. The Man Without Qualities by Robert Musil. 1,774 pages
4. Clarissa by Samuel Richardson. 1,536 pages
5. Joseph and His Brothers by Thomas Mann. 1,536 pages
6. A Suitable Boy by Vikram Seth. 1,488 pages
7. Les Misérables by Victor Hugo. 1,463 pages
8. War and Peace by Leo Tolstoy. 1,456 pages
9. Atlas Shrugged by Ayn Rand. 1,200 pages
10. Infinite Jest by David Foster Wallace. 1,079 pages