Why slow disk in VirtualBox / Docker?

Put on win7 docker toolbox - a couple of laptops. One powerful, 12Gb RAM, ssd. The second is easier - 6Gb memory hdd;
In Docker container load debian+php (7.1), the second (weak) the notebook works quite fast. On the ground - see here a picture immediately after the start of the container


Processes hanging in uninterruptable sleep (D) for 10 minutes, everything works sooo slow or not working at all (for example a web server Gateway Timeout). After some time (10 minutes) processes out of D into normal mode, but still the work is significantly slower than the "weak" laptop.

Tried the path doker in virtualbox different types of acceleration/virtualization changed the disk from dynamic to fixed, changed the disk formats - vmdk/vdi. Moved the file to the disk with ssd on the hdd.
Nothing helps.

All processes hang in D - fs communicate with the host system, all writes to the outside, works well. It is sin to disk, but perhaps it's something else.

Maybe someone has overcome this problem?