Back then 12242 used to take 3hrs 40mins from ASR to CDG.
One of the reason for slowdown of trains is more Crossings and less route capacity now.
Other is as...
more... you mentioned after New morinda (from CDG) there are like infinite number of PSRs and TSRs till Lal Kalan. Even SF trains such as 12241/42/12411/12 do not have 55kmph avg speed but railways is still collecting SF surcharge on them.