I found this, interesting thing - when untarring single member lzip compressed 
tar plzip turnes out to be apparently faster than lzip,   despite the fact that 
that archive is single member and pure decompression is faster with lzip.   It 
also has something to do with nuber of files in tar archive - when tested with 
very few files like silesia.tar,   effect did not appear.   It is not, in any 
way, life changing situation but interesting anomaly.   I wonder what could be 
a reason for that.   ~~~  $ lzip -lv binutils-2.43.tar.lz      dict   memb  
trail   uncompressed     compressed   saved  name     32 MiB     1      0      
326164480       27688115  91.51%  binutils-2.43.tar.lz   //// test   $ time 
lzip -t silesia.tar.lz   real    0m7.340s   user    0m7.260s   sys     0m0.063s 
  $ time plzip -n4 -t silesia.tar.lz   real    0m8.189s   user    0m8.105s   
sys     0m0.075s   //// untar   $ time lzip -dc binutils-2.43.tar.lz | tar -xf- 
  real    0m7.552s   user    0m5.728s   sys     0m2.363s   $ time plzip -n1 -dc 
binutils-2.43.tar.lz | tar -xf-   real    0m6.415s   user    0m6.331s   sys     
0m3.313s   $ time plzip -n4 -dc binutils-2.43.tar.lz | tar -xf-   real    
0m6.424s   user    0m6.290s   sys     0m3.370s  ~~~   More details in 
attachment.
//// binutils.tar.lz

$ lzip -lv binutils-2.43.tar.lz
   dict   memb  trail   uncompressed     compressed   saved  name
  32 MiB     1      0      326164480       27688115  91.51%  
binutils-2.43.tar.lz

//// test

$ time lzip -t binutils-2.43.tar.lz

real    0m5.340s
user    0m5.253s
sys     0m0.069s

$ time plzip -n1 -t binutils-2.43.tar.lz

real    0m5.867s
user    0m5.778s
sys     0m0.072s

$ time plzip -n2 -t binutils-2.43.tar.lz

real    0m5.868s
user    0m5.771s
sys     0m0.079s

$ time plzip -n4 -t binutils-2.43.tar.lz

real    0m5.853s
user    0m5.759s
sys     0m0.072s

//// untar

$ time lzip -dc binutils-2.43.tar.lz | tar -xf-

real    0m7.552s
user    0m5.728s
sys     0m2.363s

$ time plzip -n1 -dc binutils-2.43.tar.lz | tar -xf-

real    0m6.415s
user    0m6.331s
sys     0m3.313s

$ time plzip -n2 -dc binutils-2.43.tar.lz | tar -xf-

real    0m6.503s
user    0m6.356s
sys     0m3.321s

$ time plzip -n4 -dc binutils-2.43.tar.lz | tar -xf-

real    0m6.424s
user    0m6.290s
sys     0m3.370s


//// silesia.tar

$ lzip -lv silesia.tar.lz
   dict   memb  trail   uncompressed     compressed   saved  name
  32 MiB     1      0      211957760       48293091  77.22%  silesia.tar.lz

//// test

$ time lzip -t silesia.tar.lz

real    0m7.340s
user    0m7.260s
sys     0m0.063s

$ time plzip -n1 -t silesia.tar.lz

real    0m8.222s
user    0m8.107s
sys     0m0.082s

$ time plzip -n2 -t silesia.tar.lz

real    0m8.202s
user    0m8.094s
sys     0m0.088s

$ time plzip -n4 -t silesia.tar.lz

real    0m8.189s
user    0m8.105s
sys     0m0.075s

//// untar

$ time lzip -dc silesia.tar.lz | tar -xf-

real    0m7.846s
user    0m7.408s
sys     0m0.791s

$ time plzip -n1 -dc silesia.tar.lz | tar -xf-

real    0m8.594s
user    0m8.274s
sys     0m0.901s

$ time plzip -n2 -dc silesia.tar.lz | tar -xf-

real    0m8.515s
user    0m8.275s
sys     0m0.862s

$ time plzip -n4 -dc silesia.tar.lz | tar -xf-

real    0m8.574s
user    0m8.295s
sys     0m0.841s

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