All test performed on a Pentium G630 (Dual-core Sandy Bridge, no AES-NI).
The working directory is on tmpfs.
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    READ     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)
-serialize_reads  116               21    39    1.5    4.4 (v1.2.1-33 with -serialize_reads)
v1.3-27           113               20    11    1.4    4.2
v1.3-53-gf44902a  119               19    12    1.6    4.1
v1.3-64-g80516ed  123               19    11    1.3    4.2
v1.3-67-g9837cb0  125               19    11    1.4    4.2 (go1.8.3)
v1.3-69-ge52594d  145               19.0  11.6  1.4    4.1
v1.4-1-g3c6fe98   154               17.2  11.7  1.4    4.1
v1.4-5-g0cc6f53   182      144      16.7  11.1  1.3    3.3

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