"Build options changed, rebuilding all" even when nothing changes ==> very slow


using the Arduino 1.5.8 Software on Windows 7 with an Arduino Nano ATmega 328, I have the problem that building/compiling and uploading is very slow, 30 seconds for the “Blink” program. The program spends a long time building/compiling even if no changes have been made since the last build & upload.
Switching on verbose mode, it always says “Build options changed, rebuilding all”, even if no changes have been made since the last build (and it seems to rebuild every single library that exists, even those I have never used).

Can anyone help me make sure it only builds/compiles files that really have been changed?



Arduino 1.5.8 BETA is a pre-release version that has special support needed for Arduino Yún and Arduino Due boards. For a regular Arduino like the Nano you should be using 1.0.6.


thanks for that tip! I've uninstalled 1.5.8 and installed 1.0.6 but I still have the same issue: It rebuilds absolutely everything every time, even when no changes at all were made. So uploading Blink still takes at least half a minute, even if nothing has changed since last build/upload a minute earlier. Any ideas why this could be the case?

Thanks, Tobi

Is your system generally slow? On my MacBook Pro the Blink example compiles in under two seconds. Yes, it compiles every file included directly or indirectly:

Blink.cpp arduino/avr-libc/malloc.c arduino/avr-libc/realloc.c arduino/WInterrupts.c arduino/wiring.c arduino/wiring_analog.c arduino/wiring_digital.c arduino/wiring_pulse.c arduino/wiring_shift.c arduino/CDC.cpp arduino/HardwareSerial.cpp arduino/HID.cpp arduino/IPAddress.cpp arduino/main.cpp arduino/new.cpp arduino/Print.cpp arduino/Stream.cpp arduino/Tone.cpp arduino/USBCore.cpp arduino/WMath.cpp arduino/WString.cpp