why screen take long time to (d)etach from remote session and (R)eattach from local again?

I'm observing an issue of screen often and don't know how to handle it:
usually I go back home after work and connect from home via ssh, take 
over screen from remote and work from there.
next morning when I came back office I then need detach from remote and 
attach it back locally, but the symptom that I often see while doing 
this is:
1) hard disk flash crazy (means busy)
2) iotop tell me this:

Total DISK READ: 2.26 M/s | Total DISK WRITE: 0.00 B/s
   TID  PRIO  USER     DISK READ  DISK WRITE  SWAPIN     IO>    COMMAND
24441 be/4 ping        2.26 M/s    0.00 B/s  ?unavailable?  SCREEN -dR work1

3) system got slow in response, mostly due to HD busy , while overall 
CPU is not high at all.

this typically last for at least 3 or 5 minutes.

when I recall back It looks this happened recently when I use "-dR" , 
previously seems when I just use -r I don't remember I ever run into 
this (will try this one later).

anyone please send some hints on this..

regards
ping