The phrase 'progress slower' is correct and usable in written English.
You can use it when discussing the rate or speed at which something is progressing. For example: "John's progress in learning Spanish has been slow, but it has started to progress slower over the last few months."
Colonization by (cord-forming) basidiomycetes seems to progress slower in large diameter logs (Boddy and Heilmann-Clausen 2008).
"While we've all seen the phenomenal growth of online food delivery in B2C over the past few years, food to businesses lags significantly behind," he says, noting that legacy relationships with caterers and "the unique pressures of ordering for larger groups make innovation and progress slower".
The lowering of CCR5 cell surface expression has known clinical advantages since individuals heterozygous for the 32 bp deletion in their CCR5 gene are statistically more likely to harbor lower viral loads and progress slower in their disease course [25].
When cells are synchronized in Mitosis, they also progress slower through G1/early S phase and display later appearance of buds as compared to wild type cells (Figure S1).
Additional evidence comes from CD8+ T cell depletion studies of chronic SIV infections in monkeys [51] [53], from studies that show that MHC-heterozygous hosts progress slower to AIDS than homozygous hosts [54], and from correlates between HIV-1 disease progression and the presence or absence of certain MHC class I molecules [30], [31].
Finally, the HIV/HCV group has significant higher ratios of CD4+ T cells to viral loads than that in HIV-1 mono-infection even at month 33 visit, which may indicate that the HIV/HCV group will be likely to progress slower than the HIV-1 mono-infection group in the future.
