Page loading extremely slow and /docker/loverlay2 using large disk space

installation
3

thank you, checking it out and finding there is only a small space of the mem left

# free -h -w 1
              total        used        free      shared     buffers       cache   available
Mem:          3.8Gi       3.6Gi       100Mi       3.0Mi        15Mi       157Mi        63Mi
Swap:         6.0Gi       4.3Gi       1.7Gi

but when i use top to view cpu usage, only kswapd0 is sus taking a lot of cpu

    PID USER      PR  NI    VIRT    RES    SHR S  %CPU  %MEM     TIME+ COMMAND  
    147 root      20   0       0      0      0 S  22.1   0.0 466:10.47 kswapd0  
 838038 qisimao   25   5 6108156 159292   3332 S  14.9   4.0  14:47.47 ruby     
1128378 qisimao   20   0 5517068 147132   4732 R   7.9   3.7   0:49.06 ruby     
1131209 qisimao   20   0 5341676  84752   3664 S   6.9   2.1   0:16.10 ruby     
1131433 qisimao   20   0 5337708  87168   3860 S   6.6   2.2   0:13.29 ruby     
1131155 qisimao   20   0 5515340 105200   4208 D   6.3   2.6   0:19.56 ruby     
1128425 qisimao   20   0 5510732 128916   3876 S   5.9   3.2   0:44.48 ruby     
1131330 qisimao   20   0 5518444  80516   4556 S   5.0   2.0   0:16.18 ruby     
1131354 qisimao   20   0 5518252  84400   4400 S   4.0   2.1   0:15.52 ruby     
    386 root       0 -20       0      0      0 I   3.0   0.0  54:33.38 kworker+ 
    388 root       0 -20       0      0      0 I   2.6   0.0  54:11.81 kworker+ 
    285 root       0 -20       0      0      0 I   2.3   0.0  55:05.82 kworker+ 
    354 root       0 -20       0      0      0 I   2.3   0.0  51:55.05 kworker+ 
1131545 systemd+  20   0 1175616   8708   3912 S   1.7   0.2   0:00.99 postmas+ 
1131902 systemd+  20   0 1184152  13764   4496 R   1.7   0.3   0:01.59 postmas+ 
1127789 systemd+  20   0 1177432  11008   3144 S   1.3   0.3   0:02.86 postmas+ 
1132448 systemd+  20   0 1176508   9156   4252 S   1.3   0.2   0:00.27 postmas+ 
 285221 www-data  20   0   61904   4356   2024 S   1.0   0.1   4:19.51 nginx    
1131347 systemd+  20   0 1184764   8096   3724 D   1.0   0.2   0:01.38 postmas+ 
1131463 systemd+  20   0 1174200   8448   3900 S   1.0   0.2   0:00.17 postmas+ 
     30 root      20   0       0      0      0 S   0.7   0.0   8:01.81 ksoftir+ 
 285210 message+  20   0  133444   8476   1100 S   0.7   0.2  13:06.39 redis-s+ 
1121070 systemd+  20   0 1177628   4712   2652 S   0.7   0.1   0:04.65 postmas+ 
1123838 systemd+  20   0 1177556   5780   2916 S   0.7   0.1   0:03.40 postmas+ 
1123880 systemd+  20   0 1179840   6788   2992 S   0.7   0.2   0:03.06 postmas+ 
1131296 systemd+  20   0 1184712   7816   3732 S   0.7   0.2   0:01.62 postmas+ 
1131744 root      20   0   38636   3280   2660 R   0.7   0.1   0:01.07 top      
     10 root      20   0       0      0      0 S   0.3   0.0   4:11.79 ksoftir+ 
     24 root      20   0       0      0      0 S   0.3   0.0   4:52.74 ksoftir+ 
   1022 root      20   0   30.4g   6412   3416 S   0.3   0.2   7:22.68 BT-Task  
 285222 www-data  20   0   63016   3008   1492 S   0.3   0.1   4:06.79 nginx    
 285223 www-data  20   0   62940   3576   1832 S   0.3   0.1   4:03.03 nginx

is that normal?