hash.rb

# 50 MB + more memory
def contacts_for_vendor(vendor)	
  @_contacts_for_vendor ||=	
    Hash.new do |vendor_hash, v|	
      vendor_hash[v] =	
        contacts_for(v).select do |c|	
          v.ids.include?(c.login_id)	
        end	
    end	
  @_contacts_for_vendor[vendor]	
end

# less memory
def contacts_hash
  @_hash ||= {}
end

def contacts_for_vendor(vendor)
  contacts_hash[vendor.id] ||= contacts_for(vendor).select do |c|
    vendor.ids.include?(c.login_id)
 end
end