Effects of importing over 18000 items into repository as one commit transaction

Hi svn users,

We are rolling out a subversion install at work.
One of the teams created a FSFS repository and svn-imported a snapshot of
their entire source tree in one transaction. The resulting FSFS revision
file "1" is 261 MB and contains 18834 items. Do you think that was a bad
idea to import the entire tree in one shot?

I sort of suspect it was a bad idea because I am noticing that "svn log"
takes considerable amount of time before it dumps anything to stdout on a
repository that had only 35 checkins so far.
I've seen much better "svn log" performance on a repository with vastly
bigger number of checked in revisions, but that repository grew naturally
(it started from nothing and it grew little by little with each checkin).

Should we have imported that tree as a set of smaller checkins?
Any suggestions or hints will be very helpful.

--
Pavel Repin