Add a new --rpm-compression-level option which addresses issue 1675:

    #1675

The value can be a number from 0 to 9 inclusive. The default mirrors
the current behavior of 9. If the --rpm-compression value is set to
"none", this value is ignored.

Setting the value to 5 sped up RPM creation on my RPM from 9 to
3 minutes.

lib/fpm/package/rpm.rb

@@ -24,10 +24,10 @@ class FPM::Package::RPM < FPM::Package
 
   COMPRESSION_MAP = {
     "none" => "w0.gzdio",
-    "xz" => "w9.xzdio",
-    "xzmt" => "w9T.xzdio",
-    "gzip" => "w9.gzdio",
-    "bzip2" => "w9.bzdio"
+    "xz" => ".xzdio",
+    "xzmt" => "T.xzdio",
+    "gzip" => ".gzdio",
+    "bzip2" => ".bzdio"
   } unless defined?(COMPRESSION_MAP)
 
   option "--use-file-permissions", :flag,
@@ -68,6 +68,15 @@ class FPM::Package::RPM < FPM::Package
     value.downcase
   end
 
+  option "--compression-level", "[0-9]", "Select a compression level. 0 is store-only. 9 is max compression.",
+    :default => "9" do |value|
+    valint = value.to_i
+    unless value =~ /^\d$/ && valint >= 0 && valint <= 9
+      raise "Invalid compression level '#{value}'. Valid values are integers between 0 and 9 inclusive."
+    end
+    valint
+  end
+
   option "--compression", COMPRESSION_MAP.keys.join("|"),
     "Select a compression method. gzip works on the most platforms.",
     :default => "gzip" do |value|
@@ -602,7 +611,12 @@ def to_s(format=nil)
   end # def to_s
 
   def payload_compression
-    return COMPRESSION_MAP[attributes[:rpm_compression]]
+    if attributes[:rpm_compression] == 'none'
+      # when 'none' ignore any compression level and return w0.gzdio
+      return COMPRESSION_MAP[attributes[:rpm_compression]]
+    else
+      return "w#{attributes[:rpm_compression_level]}" + COMPRESSION_MAP[attributes[:rpm_compression]]
+    end
   end # def payload_compression
 
   def digest_algorithm