Slow reports by some chance?
It's probably worthwhile scripting a reindex of your SIMS database(s).
But first, you should know the current state. This script will show how the state of your index fragmentation. I've ignored indexes where the fragmentation is less that 25% and the page count is under 10 (these pages are likely to be cached in memory) then ordered by the page size in descending order. If you find a highly fragmented index with a lot of pages >100s then it's probably worth reindexing.
Usual disclaimers, at your own risk, etc, if you don't know about queries, do not proceed.
Capita supply a patch to reindex (14265), but it's bananas as it changes the recovery model to 'Full' (bye bye differential backups/log shipping backups - you didn;t need them, did you?) and shrinks your log file to minimum (hello autogrow, hello log file fragmentation).
SELECT OBJECT_NAME(OBJECT_ID), index_id,index_type_desc,index_level,
(DB_ID(), NULL, NULL, NULL , 'SAMPLED')
where avg_fragmentation_in_percent > 25 and page_count > 10
ORDER BY page_count DESC