diff --git a/common/src/main/java/io/netty/util/NetUtil.java b/common/src/main/java/io/netty/util/NetUtil.java
index ae4ebb598e..8634351b6a 100644
--- a/common/src/main/java/io/netty/util/NetUtil.java
+++ b/common/src/main/java/io/netty/util/NetUtil.java
@@ -291,7 +291,10 @@ public final class NetUtil {
                         }
                     }
                 } catch (Exception e) {
-                    logger.debug("Failed to get SOMAXCONN from sysctl and file {}. Default: {}", file, somaxconn, e);
+                    if (logger.isDebugEnabled()) {
+                        logger.debug("Failed to get SOMAXCONN from sysctl and file {}. Default: {}",
+                                file, somaxconn, e);
+                    }
                 } finally {
                     if (in != null) {
                         try {
diff --git a/common/src/main/java/io/netty/util/internal/NativeLibraryLoader.java b/common/src/main/java/io/netty/util/internal/NativeLibraryLoader.java
index 26d302e6e4..b05944685b 100644
--- a/common/src/main/java/io/netty/util/internal/NativeLibraryLoader.java
+++ b/common/src/main/java/io/netty/util/internal/NativeLibraryLoader.java
@@ -137,9 +137,11 @@ public final class NativeLibraryLoader {
             return;
         } catch (Throwable ex) {
             suppressed.add(ex);
-            logger.debug(
-                    "{} cannot be loaded from java.library.path, "
-                    + "now trying export to -Dio.netty.native.workdir: {}", name, WORKDIR, ex);
+            if (logger.isDebugEnabled()) {
+                logger.debug(
+                        "{} cannot be loaded from java.library.path, "
+                                + "now trying export to -Dio.netty.native.workdir: {}", name, WORKDIR, ex);
+            }
         }
 
         String libname = System.mapLibraryName(name);
diff --git a/handler/src/main/java/io/netty/handler/ssl/SslHandler.java b/handler/src/main/java/io/netty/handler/ssl/SslHandler.java
index bc24cc530e..b279abf13d 100644
--- a/handler/src/main/java/io/netty/handler/ssl/SslHandler.java
+++ b/handler/src/main/java/io/netty/handler/ssl/SslHandler.java
@@ -1163,8 +1163,10 @@ public class SslHandler extends ByteToMessageDecoder implements ChannelOutboundH
                         return true;
                     }
                 } catch (Throwable cause) {
-                    logger.debug("Unexpected exception while loading class {} classname {}",
-                                 getClass(), classname, cause);
+                    if (logger.isDebugEnabled()) {
+                        logger.debug("Unexpected exception while loading class {} classname {}",
+                                getClass(), classname, cause);
+                    }
                 }
             }
         }
diff --git a/resolver-dns/src/main/java/io/netty/resolver/dns/UnixResolverDnsServerAddressStreamProvider.java b/resolver-dns/src/main/java/io/netty/resolver/dns/UnixResolverDnsServerAddressStreamProvider.java
index e78b2337c6..feac4b9145 100644
--- a/resolver-dns/src/main/java/io/netty/resolver/dns/UnixResolverDnsServerAddressStreamProvider.java
+++ b/resolver-dns/src/main/java/io/netty/resolver/dns/UnixResolverDnsServerAddressStreamProvider.java
@@ -71,7 +71,9 @@ public final class UnixResolverDnsServerAddressStreamProvider implements DnsServ
             return nameServerCache.mayOverrideNameServers() ? nameServerCache
                                                             : DefaultDnsServerAddressStreamProvider.INSTANCE;
         } catch (Exception e) {
-            logger.debug("failed to parse {} and/or {}", ETC_RESOLV_CONF_FILE, ETC_RESOLVER_DIR, e);
+            if (logger.isDebugEnabled()) {
+                logger.debug("failed to parse {} and/or {}", ETC_RESOLV_CONF_FILE, ETC_RESOLVER_DIR, e);
+            }
             return DefaultDnsServerAddressStreamProvider.INSTANCE;
         }
     }
@@ -254,8 +256,10 @@ public final class UnixResolverDnsServerAddressStreamProvider implements DnsServ
         DnsServerAddresses existingAddresses = domainToNameServerStreamMap.put(domainName, addresses);
         if (existingAddresses != null) {
             domainToNameServerStreamMap.put(domainName, existingAddresses);
-            logger.debug("Domain name {} already maps to addresses {} so new addresses {} will be discarded",
-                    domainName, existingAddresses, addresses);
+            if (logger.isDebugEnabled()) {
+                logger.debug("Domain name {} already maps to addresses {} so new addresses {} will be discarded",
+                        domainName, existingAddresses, addresses);
+            }
         }
     }
 
diff --git a/transport/src/main/java/io/netty/channel/ChannelHandlerMask.java b/transport/src/main/java/io/netty/channel/ChannelHandlerMask.java
index dad793cf38..d307508002 100644
--- a/transport/src/main/java/io/netty/channel/ChannelHandlerMask.java
+++ b/transport/src/main/java/io/netty/channel/ChannelHandlerMask.java
@@ -173,8 +173,10 @@ final class ChannelHandlerMask {
                 try {
                     m = handlerType.getMethod(methodName, paramTypes);
                 } catch (NoSuchMethodException e) {
-                    logger.debug(
-                        "Class {} missing method {}, assume we can not skip execution", handlerType, methodName, e);
+                    if (logger.isDebugEnabled()) {
+                        logger.debug(
+                            "Class {} missing method {}, assume we can not skip execution", handlerType, methodName, e);
+                    }
                     return false;
                 }
                 return m != null && m.isAnnotationPresent(Skip.class);