Is high Extent Fragmentation a problem?
In my experience, even if you're doing full table scans, it is unlikely that extent fragmentation will affect performance much, and for more typical query patterns it should be negligible at best. That is for queries that use cached data that fits into memory - obviously fragmentation of any kind becomes rather moot if the data is in memory and isn't being read directly off disk.

Now, you've got a table that is > 8 GB, so it is possible that extent fragmentation might be harmful to your queries. If this query is using a table scan across 34 million rows, and the worst you're getting (on first execution only!) is 30 seconds, then it is extremely unlikely that lowering that extent fragmentation number is going to help much. That 30 seconds is spent loading the data into memory, and I can't fathom that improving the extent fragmentation will buy you much there. If you have the memory to spare to keep this table in memory, perhaps you should consider a startup job or some background process that periodically runs the query without forcing a user to wait for it, ensuring that it stays fresh in the cache.

Hekaton might be for you.