voltage trees take much more space than efield trees. Do we understand why?

[mjtueros]

For example, in
/sps/grand/DC2Alpha/CoREAS/sim_Dunhuang_20170401_000000_RUN1_CD_CoREAS_0000

-rw-r--r-- 1 tueros grand 12M Mar 15 05:27 adc_3205-47214_L1_0000.root
-rw-r--r-- 1 tueros grand 34M Mar 15 05:27 efield_3205-47214_L0_0000.root
-rw-r--r-- 1 tueros grand 63M Mar 15 05:27 efield_3205-47214_L1_0000.root
-rw-r--r-- 1 tueros grand 12K Mar 15 05:27 run_1_L0_0000.root
-rw-r--r-- 1 tueros grand 12K Mar 15 05:27 run_1_L1_0000.root
-rw-r--r-- 1 tueros grand 7.6K Mar 15 05:27 runefieldsim_1_L0_0000.root
-rw-r--r-- 1 tueros grand 8.3K Mar 15 05:26 runshowersim_1_L0_0000.root
-rw-r--r-- 1 tueros grand 28K Mar 15 05:27 shower_3205-47214_L0_0000.root
-rw-r--r-- 1 tueros grand 120K Mar 15 05:26 showersim_3205-47214_L0_0000.root
-rw-r--r-- 1 tueros grand 251M Mar 15 05:27 voltage_3205-47214_L0_0000.root

you can see voltage_L0 is 251M while efield_L0 is 34MB, efield_L1 is 63MB (even if it is the same lenght and lower sampling rate!) and ADC is 12MB.

I find this weird...