All test performed on tmpfs, /tmp/a mounted on /tmp/b.
The untar test uses https://cdn.kernel.org/pub/linux/kernel/v3.0/linux-3.0.tar.gz .
The archive is placed on tmpfs as well.

WRITE: dd if=/dev/zero of=zero bs=128K count=2000
UNTAR: time tar xzf ../linux-3.0.tar.gz
MD5:   time md5sum --quiet -c linux-3.0.md5sums
LS:    time ls -lR linux-3.0 > /dev/null
RM:    time rm -Rf linux-3.0

(or just run benchmark.bash)

VERSION            WRITE    UNTAR   MD5    LS     RM
v0.4                           48          1.5    5
v0.5-rc1                       56          7     19
v0.5-rc1-1                     54          4.1    9
v0.5-rc1-2                     45          1.7    3.4
v0.6                           47          1.8    4.3
v0.7                           43          1.7    4.3
v0.7.2                         26          1.8    4.3
v0.8                           23          1.8    4.3
v0.9-rc2           94          24          1.8    4.5
v0.9               94          24          1.8    4.5
v0.11             104          22          1.7    4.5
v1.1              104          20          1.5    3.4 (go1.7.1)
v1.1.1-34         112          22          1.5    3.6 (go1.7.3)
v1.2.1-33         112          21    12    1.6    4.4 (go1.8)
v1.2.1-33
-serialize_reads  116          21    39    1.5    4.4
v1.3-27           113          20    11    1.4    4.2
v1.3-53-gf44902a  119          19    12    1.6    4.1

Results for EncFS for comparison (benchmark.bash -encfs):     

VERSION            WRITE    UNTAR   MD5    LS     RM
encfs v1.9.1       95          20     8    2.8    3.8