It is interesting to note that I had a LiitoKala LG HG2 cell and even though it is rated for higher current, it had larger voltage sag. Below is the data of HG2 overlayed with green line. It seems like the LiitoKala INR18650-25R. performs slightly better than LiitoKala LG HG2 variant.
Unfortunately I do not have precise equipment to measure the internal resistances. But for most purposes the voltage curve should be sufficient. The batteries got slightly warm at 5A discharge test and no battery got too hot to touch.
