Very long compilation for simple package - ipk (opkg)

Hello i'm starting on OpenWrt and I create an simple package (ipk) for a POC on an existant openwrt system

My package have one importtant dependency, it use libmosquitto-ssl

But when I want to compile my package it take very long time to compile, because it recompile every dependency each time of mosquitto, and I dont undestand why.

I think it is not necesarry to recompile every time.

There is a setting that allows you to only use headers and ignore all dependencies compilations ?

Actualy I use openwrt 21.02 SDK for ramips mt76x8

My Make file

include $(TOPDIR)/rules.mk

PKG_NAME:=poc_mqtt
PKG_VERSION:=1.0.0
PKG_RELEASE:=1

PKG_MAINTAINER:=Alexis DEVLEESCHAUWER <alexis@devleeschauwer.fr>
PKG_LICENSE:=CC0-1.0

include $(INCLUDE_DIR)/package.mk
include $(INCLUDE_DIR)/cmake.mk

define Package/poc_mqtt
	SECTION:=utils
	# Select package by default
	#DEFAULT:=y
	CATEGORY:=Utilities
	TITLE:=POC for program use mqtt client lib in openwrt.
	DEPENDS:=+libmosquitto-ssl
endef

define Package/poc_mqtt/description
	This is some dummy application for test mqtt dependecy.
endef

define Build/Prepare
	mkdir -p $(PKG_BUILD_DIR)
	$(CP) ./src/* $(PKG_BUILD_DIR)/
endef

define Package/poc_mqtt/install
	$(INSTALL_DIR) $(1)/usr/bin
	$(INSTALL_BIN) $(PKG_BUILD_DIR)/poc_mqtt $(1)/usr/bin/
endef

$(eval $(call BuildPackage,poc_mqtt))

I have publish my poc on github if you want check https://github.com/devleesch001/openwrt-mqtt-poc

I made on bench on my computer

simple cmake result for amd64 without sdk:

cmake --build cmake-build-debug --target poc_mqtt -j 6  0,06s user 0,02s system 99% cpu 0,080 total

simple make package openwrt sdk with cross compilation result :

make package/poc_mqtt/compile -j6  651,37s user 175,65s system 187% cpu 7:21,56 total

Thank you by advance