diff --git a/CMakeLists.txt b/CMakeLists.txt
index 1b324a1..1d76991 100644
--- a/CMakeLists.txt
+++ b/CMakeLists.txt
@@ -51,7 +51,7 @@ option(3PROXY_USE_OPENSSL "Enable TLS/SSL support via OpenSSL (fallback when wol
 option(3PROXY_USE_PCRE2 "Enable PCRE2 regex filtering" ON)
 option(3PROXY_USE_PAM "Enable PAM/PamAuth" ON)
 option(3PROXY_USE_ODBC "Enable ODBC support (Unix only, always ON on Windows)" OFF)
-option(3PROXY_USE_SPLICE "Build Linux splice() support, slower than read/write for most traffic (Linux only)" OFF)
+option(3PROXY_USE_SPLICE "Build Linux splice() support, used by services given -s (Linux only)" ON)
 option(3PROXY_USE_POLL "Use poll() instead of select() (Unix only)" ON)
 option(3PROXY_USE_WSAPOLL "Use WSAPoll instead of select() (Windows only)" ON)
 option(3PROXY_USE_NETFILTER "Enable Linux netfilter support (Linux only)" ON)
@@ -664,10 +664,7 @@ foreach(PROXY_NAME proxy socks pop3p imapp smtpp ftppr tcppm udppm tlspr)
         ${CMAKE_CURRENT_SOURCE_DIR}/src
     )
 
-    target_compile_definitions(${PROXY_NAME} PRIVATE
-        WITHMAIN
-        NOPORTMAP
-    )
+    target_compile_definitions(${PROXY_NAME} PRIVATE WITHMAIN)
 
     if(NOT PROXY_NAME STREQUAL "udppm")
         target_compile_definitions(${PROXY_NAME} PRIVATE NOUDPMAIN)
@@ -679,8 +676,12 @@ foreach(PROXY_NAME proxy socks pop3p imapp smtpp ftppr tcppm udppm tlspr)
         target_compile_definitions(${PROXY_NAME} PRIVATE ANONYMOUS)
     endif()
 
+    # port mappers take port, host and port as arguments, the others options
+    # only; one of the two is defined, as in src/Makefile.inc
     if(PROXY_NAME STREQUAL "tcppm" OR PROXY_NAME STREQUAL "udppm" OR PROXY_NAME STREQUAL "tlspr")
         target_compile_definitions(${PROXY_NAME} PRIVATE PORTMAP)
+    else()
+        target_compile_definitions(${PROXY_NAME} PRIVATE NOPORTMAP)
     endif()
 
     if(WIN32)
diff --git a/Makefile.Linux b/Makefile.Linux
index e399f60..62706ca 100644
--- a/Makefile.Linux
+++ b/Makefile.Linux
@@ -4,9 +4,9 @@
 # add -DWITH_ODBC to CFLAGS and -lodbc to LIBS to compile with ODBC
 # library support. Add -DSAFESQL for poorely written ODBC library / drivers.
 #
-# Linux splice() support is not built by default, it is slower than the
-# read/write path for most traffic. Add -DWITHSPLICE to CFLAGS to build it,
-# it must additionally be enabled per service with the -s option.
+# Linux splice() support is built, but used only by services given the -s
+# option: it is faster for large transfers and slower for small requests.
+# Remove -DWITHSPLICE from CFLAGS to build without it.
 
 BUILDDIR = ../bin/
 PREFIX ?= 3proxy_
@@ -14,7 +14,7 @@ CRYPT_PREFIX ?= $(PREFIX)
 CC ?= gcc
 
 CFLAGS ?= -O3 -flto
-CFLAGS += -fno-strict-aliasing -c -pthread -D_GNU_SOURCE -DGETHOSTBYNAME_R -D_THREAD_SAFE -D_REENTRANT -DFD_SETSIZE=4096 -DWITH_POLL -DWITH_NETFILTER -D WITH_UN
+CFLAGS += -fno-strict-aliasing -c -pthread -DWITHSPLICE -D_GNU_SOURCE -DGETHOSTBYNAME_R -D_THREAD_SAFE -D_REENTRANT -DFD_SETSIZE=4096 -DWITH_POLL -DWITH_NETFILTER -D WITH_UN
 COUT = -o 
 LN ?= ${CC}
 DCFLAGS ?= -fPIC
diff --git a/doc/html/man5/3proxy.cfg.5.html b/doc/html/man5/3proxy.cfg.5.html
index a32e730..b87e0f4 100644
--- a/doc/html/man5/3proxy.cfg.5.html
+++ b/doc/html/man5/3proxy.cfg.5.html
@@ -216,12 +216,11 @@ second. Useful to minimize polling <b><br>
 -s</b> <br>
 (for admin) secure, allow only secure operations, currently
 only traffic counters view without ability to reset. <br>
-(for TCP services, Linux) enable splice(). splice() is not
-built by default and is disabled even when built, because
-current Linux does not implement SPLICE_F_MOVE, so no real
-zero-copy takes place and the read/write path is faster for
-most traffic. Rebuild with -DWITHSPLICE to make -s
-available, -s0 disables it explicitly. <b><br>
+(for TCP services, Linux) enable splice(). It is built on
+Linux by default, but off unless -s is given: splice() is
+faster for large transfers and the read/write path for small
+requests. -s0 disables it explicitly; build without
+-DWITHSPLICE to leave it out. <b><br>
 -C</b> <br>
 (for TCP services) a connection closed by any of the sides
 terminates the session, buffered data is delivered before
diff --git a/man/3proxy.cfg.5 b/man/3proxy.cfg.5
index 0d33895..0920fe6 100644
--- a/man/3proxy.cfg.5
+++ b/man/3proxy.cfg.5
@@ -194,11 +194,10 @@ delay GRACE_DELAY milliseconds before polling if average polling size is below G
  (for admin) secure, allow only secure operations, currently only traffic counters
 view without ability to reset.
 .br
- (for TCP services, Linux) enable splice(). splice() is not built by default and
-is disabled even when built, because current Linux does not implement
-SPLICE_F_MOVE, so no real zero-copy takes place and the read/write path is faster
-for most traffic. Rebuild with -DWITHSPLICE to make -s available, -s0 disables it
-explicitly.
+ (for TCP services, Linux) enable splice(). It is built on Linux by default,
+but off unless -s is given: splice() is faster for large transfers and the
+read/write path for small requests. -s0 disables it explicitly; build without
+-DWITHSPLICE to leave it out.
 .br
 .B -C
  (for TCP services) a connection closed by any of the sides terminates the