Monstrous differences.
There are 4 types, add to that you have Oracle ODBC or Crystal ODBC for Oracle.
Native is MUCH faster. ODBC is genrally second, with OLE DB trudging up behind.
It is suggested that you use the CR supplied ODBC driver if you decide to use ODBC. The Oracle driver can do some very nasty things in CR, such as changing numeric preciosion...
With regards to using CR 9 against Lawson data (very small database at this stage), here are some findings:
Native Oracle: < 1 sec
CR ODBC Oracle: < 10 seconds
Oracle ODBC: Untested, I never use this in Crystal anymore
Lawson OLE DB: < 2 minutes
Keep in mind the reason that OLE DB was slow is because it had proprietary integrated security, OLE DB is generally comparable to ODBC, though I've had it run significantly slower.
-k