So I ran the simulation script. And the results are surprising.
The drop is so low, and for such a short period of time I don't even want to make a graph for it. But I did anyway

.
The columns are as follows: Time, voltC4, voltC1
SimulationData: matrix (
[0 , 2.5 , 0 ]
, [8.0158822588692032E-7 , 2.4999999351862704 , 0.0099999999999999949 ]
, [1.6064021231348794E-6 , 2.4999998741358419 , 0.019999999999999936 ]
, [2.4144677562866118E-6 , 2.499999816879121 , 0.029999999999999872 ]
, [3.2258115070725613E-6 , 2.4999997634468883 , 0.040000000000000122 ]
, [4.0404600795783354E-6 , 2.4999997138702915 , 0.050000000000000403 ]
, [4.8584405055178202E-6 , 2.4999996681808736 , 0.060000000000000691 ]
, [5.6797801496145696E-6 , 2.4999996264105565 , 0.070000000000000973 ]
, [6.5045067150941146E-6 , 2.4999995885916582 , 0.080000000000001267 ]
, [7.3326482492899802E-6 , 2.4999995547568979 , 0.090000000000001549 ]
, [8.1642331493662643E-6 , 2.4999995249394112 , 0.10000000000000184 ]
, [8.9992901681595981E-6 , 2.4999994991727382 , 0.11000000000000213 ]
, [9.8378484201436646E-6 , 2.4999994774908419 , 0.1200000000000024 ]
, [1.0679937387519184E-5 , 2.4999994599281187 , 0.130000000000002 ]
, [1.1525586926432626E-5 , 2.499999446519401 , 0.1400000000000009 ]
, [1.237482727332704E-5 , 2.4999994372999654 , 0.14999999999999981 ]
, [1.3227689051428203E-5 , 2.4999994323055331 , 0.15999999999999869 ]
, [1.4084203277369595E-5 , 2.4999994315722925 , 0.1699999999999976 ]
, [1.4944401367959926E-5 , 2.4999994351368957 , 0.17999999999999651 ]
, [1.5808315147096707E-5 , 2.4999994430364646 , 0.18999999999999539 ]
, [1.6675976852829939E-5 , 2.4999994553086141 , 0.1999999999999943 ]
, [1.7547419144579434E-5 , 2.4999994719914458 , 0.20999999999999318 ]
, [1.8422675110510234E-5 , 2.4999994931235587 , 0.2199999999999921 ]
, [1.9301778275069997E-5 , 2.4999995187440614 , 0.22999999999999098 ]
, [2.0184762606692806E-5 , 2.4999995488925856 , 0.23999999999998989 ]
, [2.1071662525673718E-5 , 2.4999995836092851 , 0.2499999999999888 ]
, [2.1962512912218778E-5 , 2.4999996229348515 , 0.25999999999998768 ]
, [2.2857349114674918E-5 , 2.4999996669105267 , 0.26999999999998659 ]
, [2.3756206957944915E-5 , 2.4999997155781037 , 0.27999999999998547 ]
, [2.4659122752092218E-5 , 2.4999997689799437 , 0.28999999999998438 ]
, [2.5566133301140874E-5 , 2.4999998271589795 , 0.2999999999999833 ]
, [2.6477275912075862E-5 , 2.4999998901587341 , 0.30999999999998221 ]
, [2.7392588404049366E-5 , 2.4999999580233325 , 0.31999999999998106 ]
);
Simulating this also points out quite nice that C1 does not have to charge much to make the resistor division (R5sR6 and R1) at or above the ref voltage. (It is also possible never have a drop of voltage.)
The simulation shows that is of no concern in either case!!