No I don't mean they had to roll to the end. Landing on 22 most M aircraft could carry a lot of energy into NR to vacate, or a well planned roll down to LR. On 04 most M aircraft had simply ran out of speed and 'expediate right' was well used as they trundled towards the exit. This was for the majority of landings...of course a good pilot with well planned brake settings etc could still wizz of 04, but the average runway occupancy times were way higher than 22.
Displacing the threshold was supposed to shift the 'sweet spot' of perfect speed to vacate rapidly closer to an exit. But as I say on 22 there was an incentive to make first high speed to save taxy time. On 04 the incentive for most ryanairs was the 2nd exit to be closer to C and D whereas easy would try and use the first.
A standard pack gap on 04 was 4 miles, after the new exit and displaced threshold 3miles was much more frequently used, the standard for 22 thus increasingly capacity on easterlies.
hadn't been aware of the noise reasons but they make sense as well.