oxipng — oxipng.exe -o 6 --libdeflater --threads 1 --alpha --strip all

file insize instate stats outsize outstate savings
chart1.png 321684 bytes /c2 /f4 /n32
Kernel  Time =     0.000 =    0%
User    Time =     1.859 =   99%
Process Time =     1.859 =   99%    Virtual  Memory =     21 MB
Global  Time =     1.861 =  100%    Physical Memory =     18 MB
250626 bytes /c2 /f0 /n51 71058 bytes
chart2.png 574423 bytes /c2 /f4 /n23
Kernel  Time =     0.000 =    0%
User    Time =     2.468 =   99%
Process Time =     2.468 =   99%    Virtual  Memory =     26 MB
Global  Time =     2.482 =  100%    Physical Memory =     25 MB
505330 bytes /c2 /f5 /n63 69093 bytes
chart3.png 517620 bytes /c2 /f4 /n28
Kernel  Time =     0.015 =    0%
User    Time =     1.984 =   97%
Process Time =     2.000 =   97%    Virtual  Memory =     22 MB
Global  Time =     2.041 =  100%    Physical Memory =     20 MB
440749 bytes /c2 /f0 /n77 76871 bytes
chart4.png 136899 bytes /c2 /f4 /n10
Kernel  Time =     0.015 =    0%
User    Time =     1.609 =   99%
Process Time =     1.625 =  100%    Virtual  Memory =     19 MB
Global  Time =     1.616 =  100%    Physical Memory =     18 MB
124663 bytes /c2 /f5 /n11 12236 bytes
chart5.png 758590 bytes /c2 /f4 /n22
Kernel  Time =     0.031 =    1%
User    Time =     2.250 =   98%
Process Time =     2.281 =  100%    Virtual  Memory =     24 MB
Global  Time =     2.276 =  100%    Physical Memory =     20 MB
555861 bytes /c2 /f0 /n108 202729 bytes
chart6.png 309145 bytes /c2 /f4 /n25
Kernel  Time =     0.046 =    3%
User    Time =     1.500 =   97%
Process Time =     1.546 =  100%    Virtual  Memory =     18 MB
Global  Time =     1.539 =  100%    Physical Memory =     20 MB
261863 bytes /c2 /f0 /n19 47282 bytes
chart7.png 590400 bytes /c2 /f4 /n16
Kernel  Time =     0.031 =    1%
User    Time =     2.734 =   98%
Process Time =     2.765 =   99%    Virtual  Memory =     23 MB
Global  Time =     2.774 =  100%    Physical Memory =     23 MB
467813 bytes /c2 /f0 /n29 122587 bytes
chart8.png 155980 bytes /c2 /f4 /n8
Kernel  Time =     0.062 =    3%
User    Time =     1.625 =   96%
Process Time =     1.687 =  100%    Virtual  Memory =     20 MB
Global  Time =     1.676 =  100%    Physical Memory =     19 MB
122232 bytes /c2 /f0 /n19 33748 bytes
total savings 635604 bytes
total time 16,27 seconds