Production values and CGi aside (things that were due to the state of technology and budget constraints), Season 1 had an awful lot of filler material that makes it feel slow by today's standards. Basically it's a similar problem to the first half of season 5. Granted, there were hints and clues in every single episode, even the so-called stand-alone eps, but in most cases they weren't integral to the A or even B-plots. Often they were included in casual dialogue or background action (like Delenn building the Chrysalis machine) and could easily have been shifted around.
My feeling is that season 1 could have been trimmed by about 1/3rd. By this I don't mean cut out 7 episodes, but cut out filler material like the A-plot in TKO, to mention one of the worst examples, and in some other episodes, the B-plots in some episodes and recombine the remainder. It would've streamlined the whole thing without losing any hints.