Tune Ruby garbage collector to improve test speed. This is also lead to enormous memory usage. More information about GC parameters tuning could be found in follow articles: [Chapter 4.2: "Garbage collector performance tuning" in Ruby Enterprise Edition (1.8.7)](http://www.rubyenterpriseedition.com/documentation.html) ["Ruby’s GC Configuration" …

.rvmrc

# Allows to run GC less frequently which is significantly speed up specs running.
# Look for more detailed description in follow articles:
# - http://www.rubyenterpriseedition.com/documentation.html (Chapter 4.2: "Garbage collector performance tuning")
# - http://snaprails.tumblr.com/post/241746095/rubys-gc-configuration

# Initial number of heap slots. It also represents the minimum number of slots, at all times (default: 10000)
#export RUBY_HEAP_MIN_SLOTS=1000000 # for Rubies < 2.1
export RUBY_GC_HEAP_INIT_SLOTS=1000000 # for Rubies >= 2.1.0

# The number of new slots to allocate when all initial slots are used (default: 10000)
export RUBY_HEAP_SLOTS_INCREMENT=1000000

# Next time Ruby needs new heap slots it will use a multiplicator, defined by this environment variable’s value
# (default: 1.8, meaning it will allocate 18000 new slots if default settings are in use)
export RUBY_HEAP_SLOTS_GROWTH_FACTOR=1

# The number of C data structures that can be allocated before triggering the garbage collector. 
# This one is very important since the default value makes the GC run when there are still empty 
# heap slots because Rails allocates and deallocates a lot of data (default: 8000000)
export RUBY_GC_MALLOC_LIMIT=100000000

# The number of free slots that should be present after GC finishes running. 
# If there are fewer slots than those defined it will allocate new ones according 
# to RUBY_HEAP_SLOTS_INCREMENT and RUBY_HEAP_SLOTS_GROWTH_FACTOR parameters (default: 4096)
export RUBY_HEAP_FREE_MIN=500000