molasses-slow

AsimovのI, ROBOTを読んでいます。

"Hey," he shouted,"can you throw?"
"Master?"
"Never mind." Powell damned the robot's molasses-slow brain. He scrabbled up a jaggered brick-size rock. "Take this," he said, "and hit the patch of bluish crystals just across the crooked fissure. You see it?"
糖蜜は日本語では余り聞かない単語ですが、英語では "molasses" は結構出て来る単語なので知っています。しかし、"molasses-slow" とは何でしょう？ このままの形では辞書の項目にありませんでしたが、"slow as molasses"、"slow as molasses in January" という表現があることが分かりました。
・Merriam-Webster's Online Dictionary: very slow or slowly: I used to be a fast runner, but now I'm slow as molasses.
・Farlex Dictionary of Idioms: slow as molasses in January: Exceptionally slow or sluggish; not fast at all. (The addition of "January," which is among the coldest months in the Northern Hemisphere, serves to intensify the meaning, as molasses is especially viscous in the cold.): This old laptop my dad gave me takes forever booting up, and then it's as slow as molasses in January the whole time I use it!

最近のコンピュータやロボットの進歩はアシモフの想像を超える部分が多く、"robot's molasses-slow brain" は一寸あっていない気もしますが、最近のＰＣでも立ち上げには結構時間がかかるので、この表現もやはり適切なのかな。