For perl it's fast as long as you have a small payload. Here's my benchmarks using progressively bigger data structures.

perl: 5.008008
Storable: 2.21
JSON::XS: 2.25
Data::MessagePack: 0.34

==== Size ====

.-----------------+-----------+---------+---------.
| src | storable | json | msgpack |
+-----------------+-----------+---------+---------+
| 1 | 4 | fail | 1 |
| 3.14 | 8 | fail | 5 |
| {} | 7 | 2 | 1 |
| [] | 7 | 2 | 1 |
| [('a')x10] | 37 | 41 | 21 |
| {('a')x10} | 14 | fail | 11 |
| +{1,+{1,+{}}} | 29 | 14 | 7 |
| +[+[+[]]] | 19 | 6 | 3 |
'-----------------+-----------+---------+---------'
==========================

Testing: theirs:HASH (4995 bytes)

==== Serialize ====

Benchmark: running json, mp, storable for at least 1 CPU seconds...
json: 1 wallclock secs ( 1.14 usr + 0.00 sys = 1.14 CPU) @ 26947.37/s (n=30720)
mp: 1 wallclock secs ( 1.11 usr + 0.00 sys = 1.11 CPU) @ 70446.85/s (n=78196)
storable: 1 wallclock secs ( 1.06 usr + 0.00 sys = 1.06 CPU) @ 18442.45/s (n=19549)
Rate storable json mp
storable 18442/s -- -32% -74%
json 26947/s 46% -- -62%
mp 70447/s 282% 161% --

==== Deserialize ====

Benchmark: running json, mp, storable for at least 1 CPU seconds...
json: 1 wallclock secs ( 1.02 usr + 0.00 sys = 1.02 CPU) @ 23424.51/s (n=23893)
mp: 1 wallclock secs ( 1.02 usr + 0.00 sys = 1.02 CPU) @ 35136.27/s (n=35839)
storable: 1 wallclock secs ( 1.06 usr + 0.00 sys = 1.06 CPU) @ 25357.55/s (n=26879)
Rate json storable mp
json 23425/s -- -8% -33%
storable 25358/s 8% -- -28%
mp 35136/s 50% 39% --

==========================

Testing: xdbi:HASH (24138 bytes)

==== Serialize ====

Benchmark: running json, mp, storable for at least 1 CPU seconds...
json: 1 wallclock secs ( 1.06 usr + 0.00 sys = 1.06 CPU) @ 2414.15/s (n=2559)
mp: 1 wallclock secs ( 1.07 usr + 0.00 sys = 1.07 CPU) @ 8373.83/s (n=8960)
storable: 1 wallclock secs ( 1.06 usr + 0.00 sys = 1.06 CPU) @ 7244.34/s (n=7679)
Rate json storable mp
json 2414/s -- -67% -71%
storable 7244/s 200% -- -13%
mp 8374/s 247% 16% --

==== Deserialize ====

Benchmark: running json, mp, storable for at least 1 CPU seconds...
json: 1 wallclock secs ( 1.11 usr + 0.00 sys = 1.11 CPU) @ 4842.34/s (n=5375)
mp: 2 wallclock secs ( 1.13 usr + 0.00 sys = 1.13 CPU) @ 4324.78/s (n=4887)
storable: 1 wallclock secs ( 1.05 usr + 0.00 sys = 1.05 CPU) @ 4654.29/s (n=4887)
Rate mp storable json
mp 4325/s -- -7% -11%
storable 4654/s 8% -- -4%
json 4842/s 12% 4% --

==========================

Testing: pdf:HASH (35239 bytes)

==== Serialize ====

Benchmark: running json, mp, storable for at least 1 CPU seconds...
json: 1 wallclock secs ( 1.04 usr + 0.00 sys = 1.04 CPU) @ 9845.19/s (n=10239)
mp: 1 wallclock secs ( 1.05 usr + 0.00 sys = 1.05 CPU) @ 5119.05/s (n=5375)
storable: 1 wallclock secs ( 1.10 usr + 0.00 sys = 1.10 CPU) @ 7518.18/s (n=8270)
Rate mp storable json
mp 5119/s -- -32% -48%
storable 7518/s 47% -- -24%
json 9845/s 92% 31% --

==== Deserialize ====

Benchmark: running json, mp, storable for at least 1 CPU seconds...
json: 1 wallclock secs ( 1.08 usr + 0.00 sys = 1.08 CPU) @ 3110.19/s (n=3359)
mp: 1 wallclock secs ( 1.07 usr + 0.00 sys = 1.07 CPU) @ 2790.65/s (n=2986)
storable: 1 wallclock secs ( 1.08 usr + 0.00 sys = 1.08 CPU) @ 3554.63/s (n=3839)
Rate mp json storable
mp 2791/s -- -10% -21%
json 3110/s 11% -- -13%
storable 3555/s 27% 14% --

==========================

Testing: globallib:HASH (197319 bytes)

==== Serialize ====

Benchmark: running json, mp, storable for at least 1 CPU seconds...
json: 1 wallclock secs ( 1.09 usr + 0.00 sys = 1.09 CPU) @ 1760.55/s (n=1919)
mp: 1 wallclock secs ( 1.06 usr + 0.00 sys = 1.06 CPU) @ 791.51/s (n=839)
storable: 1 wallclock secs ( 1.05 usr + 0.00 sys = 1.05 CPU) @ 1279.05/s (n=1343)
Rate mp storable json
mp 792/s -- -38% -55%
storable 1279/s 62% -- -27%
json 1761/s 122% 38% --

==== Deserialize ====

Benchmark: running json, mp, storable for at least 1 CPU seconds...
json: 1 wallclock secs ( 1.71 usr + 0.00 sys = 1.71 CPU) @ 301.75/s (n=516)
mp: 1 wallclock secs ( 1.03 usr + 0.00 sys = 1.03 CPU) @ 404.85/s (n=417)
storable: 1 wallclock secs ( 1.12 usr + 0.00 sys = 1.12 CPU) @ 544.64/s (n=610)
Rate json mp storable
json 302/s -- -25% -45%
mp 405/s 34% -- -26%
storable 545/s 80% 35% --