It is impossible in the first place and unnecessary in the second place because not everything is of equal importance. Spend more time listening and attempt to take down the main points. If you are writing as fast as you can, you cannot be as discriminating a listener. There may be some times, however, when it is more important to write than to think. Listen for cues as to important points, transition form one point to the next, repetition of points for emphasis, changes in voice inflections, enumeration of a series of points, etc.
Many lecturers attempt to present a few major points and several minor points in a lecture.
The rest is explanatory material and samples. Try to see the main points and do not get lost in a barrage of minor points which do not seem related to each other. The relationship is there if you will listen for it. Be alert to cues about what the professor thinks is important. Make your original notes legible enough for your own reading, but use abbreviations of your own invention when possible.