In the Arduino IDE do this: - File > Preferences > Show verbose output during: > upload (check) > OK - Tools > Burn Bootloader After it finishes examine the output in the black console window at the bottom of the Arduino IDE window. If you look carefully you'll see that the Arduino IDE actually runs two separate AVRDUDE commands when you **Burn Bootloader**. The first sets the fuses according to the settings in boards.txt for the selected board, the second actually burns the bootloader. So your comparison is not really fair unless you run both commands in your test of using AVRDUDE directly. ##Edit by OP: Full output in the Arduino IDE: D:\Programme\Arduino\hardware\tools\avr/bin/avrdude -CD:\Programme\Arduino\hardware\tools\avr/etc/avrdude.conf -v -patmega32u4 -cstk500v1 -PCOM4 -b19200 -e -Ulock:w:0x3F:m -Uefuse:w:0xcb:m -Uhfuse:w:0xd8:m -Ulfuse:w:0xff:m avrdude: Version 6.3, compiled on Sep 12 2016 at 17:24:16 Copyright (c) 2000-2005 Brian Dean, http://www.bdmicro.com/ Copyright (c) 2007-2014 Joerg Wunsch System wide configuration file is "D:\Programme\Arduino\hardware\tools\avr/etc/avrdude.conf" Using Port : COM4 Using Programmer : stk500v1 Overriding Baud Rate : 19200 AVR Part : ATmega32U4 Chip Erase delay : 9000 us PAGEL : PD7 BS2 : PA0 RESET disposition : dedicated RETRY pulse : SCK serial program mode : yes parallel program mode : yes Timeout : 200 StabDelay : 100 CmdexeDelay : 25 SyncLoops : 32 ByteDelay : 0 PollIndex : 3 PollValue : 0x53 Memory Detail : Block Poll Page Polled Memory Type Mode Delay Size Indx Paged Size Size #Pages MinW MaxW ReadBack ----------- ---- ----- ----- ---- ------ ------ ---- ------ ----- ----- --------- eeprom 65 20 4 0 no 1024 4 0 9000 9000 0x00 0x00 flash 65 6 128 0 yes 32768 128 256 4500 4500 0x00 0x00 lfuse 0 0 0 0 no 1 0 0 9000 9000 0x00 0x00 hfuse 0 0 0 0 no 1 0 0 9000 9000 0x00 0x00 efuse 0 0 0 0 no 1 0 0 9000 9000 0x00 0x00 lock 0 0 0 0 no 1 0 0 9000 9000 0x00 0x00 calibration 0 0 0 0 no 1 0 0 0 0 0x00 0x00 signature 0 0 0 0 no 3 0 0 0 0 0x00 0x00 Programmer Type : STK500 Description : Atmel STK500 Version 1.x firmware Hardware Version: 2 Firmware Version: 1.18 Topcard : Unknown Vtarget : 0.0 V Varef : 0.0 V Oscillator : Off SCK period : 0.1 us avrdude: AVR device initialized and ready to accept instructions Reading | ################################################## | 100% 0.02s avrdude: Device signature = 0x1e9587 (probably m32u4) avrdude: erasing chip avrdude: reading input file "0x3F" avrdude: writing lock (1 bytes): D:\Programme\Arduino\hardware\tools\avr/bin/avrdude -CD:\Programme\Arduino\hardware\tools\avr/etc/avrdude.conf -v -patmega32u4 -cstk500v1 -PCOM4 -b19200 -Uflash:w:D:\Programme\Arduino\hardware\arduino\avr/bootloaders/caterina/Caterina-Micro.hex:i -Ulock:w:0x2F:m Writing | ################################################## | 100% 0.01s avrdude: 1 bytes of lock written avrdude: verifying lock memory against 0x3F: avrdude: load data lock data from input file 0x3F: avrdude: input file 0x3F contains 1 bytes avrdude: reading on-chip lock data: Reading | ################################################## | 100% 0.01s avrdude: verifying ... avrdude: 1 bytes of lock verified avrdude: reading input file "0xcb" avrdude: writing efuse (1 bytes): Writing | ################################################## | 100% 0.01s avrdude: 1 bytes of efuse written avrdude: verifying efuse memory against 0xcb: avrdude: load data efuse data from input file 0xcb: avrdude: input file 0xcb contains 1 bytes avrdude: reading on-chip efuse data: Reading | ################################################## | 100% 0.01s avrdude: verifying ... avrdude: 1 bytes of efuse verified avrdude: reading input file "0xd8" avrdude: writing hfuse (1 bytes): Writing | ################################################## | 100% 0.01s avrdude: 1 bytes of hfuse written avrdude: verifying hfuse memory against 0xd8: avrdude: load data hfuse data from input file 0xd8: avrdude: input file 0xd8 contains 1 bytes avrdude: reading on-chip hfuse data: Reading | ################################################## | 100% 0.01s avrdude: verifying ... avrdude: 1 bytes of hfuse verified avrdude: reading input file "0xff" avrdude: writing lfuse (1 bytes): Writing | ################################################## | 100% 0.01s avrdude: 1 bytes of lfuse written avrdude: verifying lfuse memory against 0xff: avrdude: load data lfuse data from input file 0xff: avrdude: input file 0xff contains 1 bytes avrdude: reading on-chip lfuse data: Reading | ################################################## | 100% 0.01s avrdude: verifying ... avrdude: 1 bytes of lfuse verified avrdude done. Thank you. avrdude: Version 6.3, compiled on Sep 12 2016 at 17:24:16 Copyright (c) 2000-2005 Brian Dean, http://www.bdmicro.com/ Copyright (c) 2007-2014 Joerg Wunsch System wide configuration file is "D:\Programme\Arduino\hardware\tools\avr/etc/avrdude.conf" Using Port : COM4 Using Programmer : stk500v1 Overriding Baud Rate : 19200 AVR Part : ATmega32U4 Chip Erase delay : 9000 us PAGEL : PD7 BS2 : PA0 RESET disposition : dedicated RETRY pulse : SCK serial program mode : yes parallel program mode : yes Timeout : 200 StabDelay : 100 CmdexeDelay : 25 SyncLoops : 32 ByteDelay : 0 PollIndex : 3 PollValue : 0x53 Memory Detail : Block Poll Page Polled Memory Type Mode Delay Size Indx Paged Size Size #Pages MinW MaxW ReadBack ----------- ---- ----- ----- ---- ------ ------ ---- ------ ----- ----- --------- eeprom 65 20 4 0 no 1024 4 0 9000 9000 0x00 0x00 flash 65 6 128 0 yes 32768 128 256 4500 4500 0x00 0x00 lfuse 0 0 0 0 no 1 0 0 9000 9000 0x00 0x00 hfuse 0 0 0 0 no 1 0 0 9000 9000 0x00 0x00 efuse 0 0 0 0 no 1 0 0 9000 9000 0x00 0x00 lock 0 0 0 0 no 1 0 0 9000 9000 0x00 0x00 calibration 0 0 0 0 no 1 0 0 0 0 0x00 0x00 signature 0 0 0 0 no 3 0 0 0 0 0x00 0x00 Programmer Type : STK500 Description : Atmel STK500 Version 1.x firmware Hardware Version: 2 Firmware Version: 1.18 Topcard : Unknown Vtarget : 0.0 V Varef : 0.0 V Oscillator : Off SCK period : 0.1 us avrdude: AVR device initialized and ready to accept instructions Reading | ################################################## | 100% 0.02s avrdude: Device signature = 0x1e9587 (probably m32u4) avrdude: NOTE: "flash" memory has been specified, an erase cycle will be performed To disable this feature, specify the -D option. avrdude: erasing chip avrdude: reading input file "D:\Programme\Arduino\hardware\arduino\avr/bootloaders/caterina/Caterina-Micro.hex" avrdude: writing flash (32730 bytes): Writing | ################################################## | 100% 35.65s avrdude: 32730 bytes of flash written avrdude: verifying flash memory against D:\Programme\Arduino\hardware\arduino\avr/bootloaders/caterina/Caterina-Micro.hex: avrdude: load data flash data from input file D:\Programme\Arduino\hardware\arduino\avr/bootloaders/caterina/Caterina-Micro.hex: avrdude: input file D:\Programme\Arduino\hardware\arduino\avr/bootloaders/caterina/Caterina-Micro.hex contains 32730 bytes avrdude: reading on-chip flash data: Reading | ################################################## | 100% 19.92s avrdude: verifying ... avrdude: 32730 bytes of flash verified avrdude: reading input file "0x2F" avrdude: writing lock (1 bytes): Writing | ################################################## | 100% 0.02s avrdude: 1 bytes of lock written avrdude: verifying lock memory against 0x2F: avrdude: load data lock data from input file 0x2F: avrdude: input file 0x2F contains 1 bytes avrdude: reading on-chip lock data: Reading | ################################################## | 100% 0.01s avrdude: verifying ... avrdude: 1 bytes of lock verified avrdude done. Thank you.