Beyond obvious constraints in the case of nutrient limitation, what can explain the relatively slow growth rate of cells in rich media?
Lab strains of E. coli grow really, really fast. The cell cycle in rich media is even faster that the genomic replication (!). But for many other organisms, that is not true. Is there anything else, beyond the lack of food / environmental signals that can act as intrinsinc barriers to the growth rate of cells, assuming that parameters like pH, temperature and oxygenation are properly chosen?
For example some cells have genomes about the same size as S. cerevisiae but divide much, much slower, why is that? Is it necessarily a sign that something in their growth medium is lacking? Maybe checkpoint kinetics (if so, can the issue be fixed by mutating cyclins, for example)?