diff --git a/tools/Makefile.am b/tools/Makefile.am
index f6df70ffa2..b785a07a19 100644
--- a/tools/Makefile.am
+++ b/tools/Makefile.am
@@ -96,14 +96,15 @@ AM_LDFLAGS = \
 	$(xnone)
 
 EXTRA_DIST = \
-	defcheck.py			\
-	gimp-mkenums			\
-	gimppath2svg.py			\
-	mnemonic-clashes		\
-	performance-log-close-tags.py	\
-	performance-log-coalesce.py	\
-	performance-log-deduce.py	\
-	performance-log-expand.py	\
-	performance-log-resolve.py	\
-	performance-log-viewer		\
+	defcheck.py				\
+	gimp-mkenums				\
+	gimppath2svg.py				\
+	mnemonic-clashes			\
+	performance-log-close-tags.py		\
+	performance-log-coalesce.py		\
+	performance-log-deduce.py		\
+	performance-log-expand.py		\
+	performance-log-progressive-coalesce.py	\
+	performance-log-resolve.py		\
+	performance-log-viewer			\
 	performance-log-viewer.py
diff --git a/tools/performance-log-progressive-coalesce.py b/tools/performance-log-progressive-coalesce.py
new file mode 100755
index 0000000000..1942e5ffce
--- /dev/null
+++ b/tools/performance-log-progressive-coalesce.py
@@ -0,0 +1,54 @@
+#!/usr/bin/env python3
+
+"""
+performance-log-progressive-coalesce.py -- Coalesce address-maps in progressive
+GIMP performance logs
+Copyright (C) 2020  Ell
+
+This program is free software: you can redistribute it and/or modify
+it under the terms of the GNU General Public License as published by
+the Free Software Foundation; either version 3 of the License, or
+(at your option) any later version.
+
+This program is distributed in the hope that it will be useful,
+but WITHOUT ANY WARRANTY; without even the implied warranty of
+MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+GNU General Public License for more details.
+
+You should have received a copy of the GNU General Public License
+along with this program.  If not, see <https://www.gnu.org/licenses/>.
+
+
+Usage: performance-log-progressive-coalesce.py < infile > outfile
+"""
+
+from xml.etree import ElementTree
+import sys
+
+empty_element = ElementTree.Element ("")
+
+# Read performance log from STDIN
+log = ElementTree.fromstring (sys.stdin.buffer.read ())
+
+samples = log.find ("samples") or empty_element
+
+address_map = log.find ("address-map")
+
+if not address_map:
+    address_map = ElementTree.Element ("address-map")
+
+# Coalesce partial address maps
+for partial_address_map in samples.iterfind ("address-map"):
+    for element in partial_address_map:
+        address_map.append (element)
+
+# Remove partial address maps
+for partial_address_map in samples.iterfind ("address-map"):
+    samples.remove (partial_address_map)
+
+# Add global address map
+if not log.find ("address-map") and len (address_map) > 0:
+    log.append (address_map)
+
+# Write performance log to STDOUT
+sys.stdout.buffer.write (ElementTree.tostring (log))
diff --git a/tools/performance-log-viewer b/tools/performance-log-viewer
index f3aa5612ae..2ef7f38b85 100755
--- a/tools/performance-log-viewer
+++ b/tools/performance-log-viewer
@@ -30,9 +30,10 @@ file="$1"
 
 < "$file" || exit 1
 
-< "$file"                                    \
-"$tools_dir/performance-log-close-tags.py" | \
-"$tools_dir/performance-log-expand.py"     | \
-"$tools_dir/performance-log-coalesce.py"   | \
-"$tools_dir/performance-log-deduce.py"     | \
+< "$file"                                              \
+"$tools_dir/performance-log-close-tags.py"           | \
+"$tools_dir/performance-log-progressive-coalesce.py" | \
+"$tools_dir/performance-log-expand.py"               | \
+"$tools_dir/performance-log-coalesce.py"             | \
+"$tools_dir/performance-log-deduce.py"               | \
 "$tools_dir/performance-log-viewer.py"