slow burn
A gradual development that increases in strength or power over time. It's going to be a slow burn before we start earning serious money on this app. The rebellion against the government had been a slow burn, as decades of mistreatment slowly fueled the fires of unrest.
a slow burn
A slow burn is a feeling or effect that develops gradually. In a single weekend the slow burn of public disgust turned into a bonfire. He promised a slow burn campaign over the next 18 months to support the idea of economic change. Note: In American English, people say that someone does a slow burn if they gradually become more and more angry. Wilson, sensing a challenge to his power, did a slow burn.