doc/news.texi |  8 ++++++++
 ood.go        | 24 +++++++++++++++++++++++-
 usage.go      |  2 +-

diff --git a/doc/news.texi b/doc/news.texi
index 5e91fea61bda22a9823b601e2ba12fac27211a0376c25ee5a378be725394c019..5b5453dac605fee68348414674b6460a98a508663aad9e5a0363cdb3c8569b4f 100644
--- a/doc/news.texi
+++ b/doc/news.texi
@@ -2,6 +2,14 @@ @node News
 @cindex news
 @unnumbered News
 
+@anchor{Release 1_27_0}
+@section Release 1.27.0
+@itemize
+@item
+    Improved out-of-date check and @file{.do} files search performance,
+    because of caching their results.
+@end itemize
+
 @anchor{Release 1_26_0}
 @section Release 1.26.0
 @itemize
diff --git a/ood.go b/ood.go
index 024757a998469f2734c29a73a0b502e76619e3dbaba8019fa62259134d12d4c0..2b65f0b335f5a110958346d9d3e8b3f38dc2c1292d50f04bafe9eeb02616f006 100644
--- a/ood.go
+++ b/ood.go
@@ -47,6 +47,7 @@ 	OODTgts       map[string]struct{}
 	FdOODTgts     *os.File
 	FdOODTgtsLock *os.File
 
+	OODCache        map[string]bool = make(map[string]bool)
 	FileExistsCache map[string]bool = make(map[string]bool)
 
 	ErrMissingTarget = errors.New("invalid format of .rec: missing Target")
@@ -128,10 +129,16 @@ func isOOD(cwd, tgtOrig string, level int, seen map[string]struct{}) (bool, error) {
 	indent := strings.Repeat(". ", level)
 	tracef(CDebug, "ood: %s%s checking", indent, tgtOrig)
 	cwd, tgt := cwdAndTgt(path.Join(cwd, tgtOrig))
+	ood, cached := OODCache[path.Join(cwd, tgt)]
+	if cached {
+		tracef(CDebug, "ood: %s%s -> cached: %v", indent, tgtOrig, ood)
+		return ood, nil
+	}
 	depPath := path.Join(cwd, RedoDir, tgt+DepSuffix)
 	fdDep, err := os.Open(depPath)
 	if err != nil {
 		tracef(CDebug, "ood: %s%s -> no dep: %s", indent, tgtOrig, depPath)
+		OODCache[path.Join(cwd, tgt)] = true
 		return true, nil
 	}
 	depInfo, err := depRead(fdDep)
@@ -142,13 +149,14 @@ 	}
 
 	if depInfo.build == BuildUUID {
 		tracef(CDebug, "ood: %s%s -> already built", indent, tgtOrig)
+		OODCache[path.Join(cwd, tgt)] = false
 		return false, nil
 	}
 	if !FileExists(path.Join(cwd, tgt)) {
 		tracef(CDebug, "ood: %s%s -> non-existent", indent, tgtOrig)
+		OODCache[path.Join(cwd, tgt)] = true
 		return true, nil
 	}
-	ood := false
 
 	for _, dep := range depInfo.ifcreates {
 		if FileExists(path.Join(cwd, dep)) {
@@ -169,12 +177,21 @@ 			return ood, TgtError{tgtOrig, fmt.Errorf("invalid format of .rec: %w", err)}
 		}
 		theirHsh := m["Hash"]
 		tracef(CDebug, "ood: %s%s -> %s: checking", indent, tgtOrig, dep)
+		ood, cached = OODCache[path.Join(cwd, dep)]
+		if cached {
+			tracef(CDebug, "ood: %s%s -> %s: cached: %v", indent, tgtOrig, dep, ood)
+			if ood {
+				goto Done
+			}
+			continue
+		}
 
 		inode, err := inodeFromFileByPath(path.Join(cwd, dep))
 		if err != nil {
 			if os.IsNotExist(err) {
 				tracef(CDebug, "ood: %s%s -> %s: not exists", indent, tgtOrig, dep)
 				ood = true
+				OODCache[path.Join(cwd, dep)] = ood
 				goto Done
 			}
 			return ood, TgtError{tgtOrig, err}
@@ -183,6 +200,7 @@
 		if inode.Size != theirInode.Size {
 			tracef(CDebug, "ood: %s%s -> %s: size differs", indent, tgtOrig, dep)
 			ood = true
+			OODCache[path.Join(cwd, dep)] = ood
 			goto Done
 		}
 		if InodeTrust != InodeTrustNone && inode.Equals(theirInode) {
@@ -201,6 +219,7 @@ 			}
 			if theirHsh != hsh {
 				tracef(CDebug, "ood: %s%s -> %s: hash differs", indent, tgtOrig, dep)
 				ood = true
+				OODCache[path.Join(cwd, dep)] = ood
 				goto Done
 			}
 			tracef(CDebug, "ood: %s%s -> %s: same hash", indent, tgtOrig, dep)
@@ -212,11 +231,13 @@ 			continue
 		}
 		if isSrc(cwd, dep) {
 			tracef(CDebug, "ood: %s%s -> %s: is source", indent, tgtOrig, dep)
+			OODCache[path.Join(cwd, dep)] = false
 			continue
 		}
 
 		if _, ok := seen[cwdMustRel(cwd, dep)]; ok {
 			tracef(CDebug, "ood: %s%s -> %s: was always built", indent, tgtOrig, dep)
+			OODCache[path.Join(cwd, dep)] = false
 			continue
 		}
 
@@ -234,6 +255,7 @@ 	}
 
 Done:
 	tracef(CDebug, "ood: %s%s: %v", indent, tgtOrig, ood)
+	OODCache[path.Join(cwd, tgt)] = ood
 	return ood, nil
 }
 
diff --git a/usage.go b/usage.go
index 7ba89b46961f16087914c9875cf530a07b629ac4aa8eebe25025d4050e54c9b5..9abaa9c4d2490cc4f8e9ec22f1fe6002d624b391600fad082a7976fb9e7baa0b 100644
--- a/usage.go
+++ b/usage.go
@@ -24,7 +24,7 @@ 	"os"
 )
 
 const (
-	Version  = "1.26.0"
+	Version  = "1.27.0"
 	Warranty = `Copyright (C) 2020-2022 Sergey Matveev
 
 This program is free software: you can redistribute it and/or modify