diff --git a/CHANGES b/CHANGES
index 929d9c9155..907ff0de34 100644
--- a/CHANGES
+++ b/CHANGES
@@ -1,3 +1,9 @@
+6072.	[bug]		Avoid the OpenSSL lock contention when initializing
+			Message Digest Contexts by using explicit algorithm
+			fetching, initializing static contexts for every
+			supported algorithms, and initializing the new context
+			by copying the static copy. [GL #3795]
+
 6069.	[bug]		Detach from the view in zone_shutdown() to
 			release the memory held by the dead view
 			early. [GL #3801]
diff --git a/doc/notes/notes-current.rst b/doc/notes/notes-current.rst
index 1e00dde0c2..c4fc060d68 100644
--- a/doc/notes/notes-current.rst
+++ b/doc/notes/notes-current.rst
@@ -39,6 +39,9 @@ Bug Fixes
   cause increased memory consumption due to delayed cleaning of view memory.
   This has been fixed. :gl:`#3801`
 
+- Improve the speed of the message digest algorithms (MD5, SHA-1,
+  SHA-2) and NSEC3 hashing. :gl:`#3795`
+
 Known Issues
 ~~~~~~~~~~~~
 
diff --git a/lib/isc/iterated_hash.c b/lib/isc/iterated_hash.c
index 14c63fb7f7..de1f3a36a3 100644
--- a/lib/isc/iterated_hash.c
+++ b/lib/isc/iterated_hash.c
@@ -13,64 +13,122 @@
 
 #include <stdio.h>
 
+#include <openssl/opensslv.h>
+
 #include <isc/iterated_hash.h>
-#include <isc/md.h>
 #include <isc/util.h>
 
+#if OPENSSL_VERSION_NUMBER < 0x30000000L || OPENSSL_API_LEVEL < 30000
+
+#include <openssl/sha.h>
+
 int
 isc_iterated_hash(unsigned char *out, const unsigned int hashalg,
 		  const int iterations, const unsigned char *salt,
 		  const int saltlength, const unsigned char *in,
 		  const int inlength) {
-	isc_md_t *md;
-	isc_result_t result;
+	REQUIRE(out != NULL);
+
 	int n = 0;
-	unsigned int outlength = 0;
 	size_t len;
 	const unsigned char *buf;
-
-	REQUIRE(out != NULL);
+	SHA_CTX ctx;
 
 	if (hashalg != 1) {
 		return (0);
 	}
 
-	if ((md = isc_md_new()) == NULL) {
+	buf = in;
+	len = inlength;
+
+	do {
+		if (SHA1_Init(&ctx) != 1) {
+			return (0);
+		}
+
+		if (SHA1_Update(&ctx, buf, len) != 1) {
+			return (0);
+		}
+
+		if (SHA1_Update(&ctx, salt, saltlength) != 1) {
+			return (0);
+		}
+
+		if (SHA1_Final(out, &ctx) != 1) {
+			return (0);
+		}
+
+		buf = out;
+		len = SHA_DIGEST_LENGTH;
+	} while (n++ < iterations);
+
+	return (SHA_DIGEST_LENGTH);
+}
+
+#else
+
+#include <openssl/evp.h>
+
+#include <isc/md.h>
+
+int
+isc_iterated_hash(unsigned char *out, const unsigned int hashalg,
+		  const int iterations, const unsigned char *salt,
+		  const int saltlength, const unsigned char *in,
+		  const int inlength) {
+	REQUIRE(out != NULL);
+
+	int n = 0;
+	size_t len;
+	unsigned int outlength = 0;
+	const unsigned char *buf;
+	EVP_MD_CTX *ctx;
+	;
+	EVP_MD *md;
+
+	if (hashalg != 1) {
 		return (0);
 	}
 
-	len = inlength;
+	ctx = EVP_MD_CTX_new();
+	RUNTIME_CHECK(ctx != NULL);
+	md = EVP_MD_fetch(NULL, "SHA1", NULL);
+	RUNTIME_CHECK(md != NULL);
+
 	buf = in;
+	len = inlength;
+
 	do {
-		result = isc_md_init(md, ISC_MD_SHA1);
-		if (result != ISC_R_SUCCESS) {
-			goto md_fail;
+		if (EVP_DigestInit_ex(ctx, md, NULL) != 1) {
+			goto fail;
 		}
-		result = isc_md_update(md, buf, len);
-		if (result != ISC_R_SUCCESS) {
-			goto md_fail;
+
+		if (EVP_DigestUpdate(ctx, buf, len) != 1) {
+			goto fail;
 		}
-		result = isc_md_update(md, salt, saltlength);
-		if (result != ISC_R_SUCCESS) {
-			goto md_fail;
+
+		if (EVP_DigestUpdate(ctx, salt, saltlength) != 1) {
+			goto fail;
 		}
-		result = isc_md_final(md, out, &outlength);
-		if (result != ISC_R_SUCCESS) {
-			goto md_fail;
-		}
-		result = isc_md_reset(md);
-		if (result != ISC_R_SUCCESS) {
-			goto md_fail;
+
+		if (EVP_DigestFinal_ex(ctx, out, &outlength) != 1) {
+			goto fail;
 		}
+
 		buf = out;
 		len = outlength;
 	} while (n++ < iterations);
 
-	isc_md_free(md);
+	EVP_MD_CTX_free(ctx);
+	EVP_MD_free(md);
 
 	return (outlength);
-md_fail:
-	isc_md_free(md);
+
+fail:
+	EVP_MD_CTX_free(ctx);
+	EVP_MD_free(md);
+
 	return (0);
 }
-#undef RETERR
+
+#endif