Import data from binary file is very slow - performance

Question

I have a folder full of .txt files that contain test data. I wrote a macro to sift through the .txt files to extract the information I want based on some search criteria and then write those search results into a binary file.
So now that I have a binary file that contains a reduced data set, I wrote another macro to search binary file for what I actually want.
For some reason, my macro is very slow to read in data from the binary file.
As a comparison, I wrote a macro that looked through all txt files for a specific search, wrote that into binary file, and then just read that back into Excel. That only took 60 seconds.
Here's a snippet. I'm wondering if the if-else statement to check if it matches my search criteria [LC(a) and EID(e)] is slowing things down or size of binary file (only 200 MB).
Type MyBinaryRecordInfo
MyBinaryRecordInfo1(1 To 12) As String ' variable length
End Type
i = 1
Open currentpath & "\" & bin_fname & ".DAT" For Binary As #f
' read records from the binary file
For a = 1 To totalLC
For e = 1 To totalElm
Do While Loc(f) < LOF(f)
Call ReadBinRecord(MyRecord, f, ElmType)
Sheets(ElmType).Select
If MyRecord.MyBinaryRecordInfo1(1) = LC(a) Then
If MyRecord.MyBinaryRecordInfo1(2) = EID(e) Then
For j = 1 To totalbinrec
With MyRecord
Cells(i + 3, j) = .MyBinaryRecordInfo1(j)
End With
Next j
i = i + 1
Exit Do
End If
End If
Loop
Next e
Next a
Close #f ' close the file
Sub ReadBinRecord(MyRecord As MyBinaryRecordInfo, f As Integer, ElmType As String)
' reads the next record from an open binary file
Dim intSize As Integer
For j = 1 To totalbinrec
With MyRecord
Get f, , intSize ' read the size of the ID field
.MyBinaryRecordInfo1(j) = String(intSize, " ") ' set the variable length
Get f, , .MyBinaryRecordInfo1(j) ' read the variable string field
End With
Next j

Answer 1

Possibly the slow part is writing out to Excel. In particular, you change the sheet every time you read the row
Assuming you know the number of rows in the binary file in advance, you can read into memory and then write out once at the end. The code would look something like the following:
Option Explicit
Type MyBinaryRecordInfo
MyBinaryRecordInfo1(1 To 12) As String ' variable length
End Type
Sub x()
num_rows = 5000
Open currentpath & "\" & bin_fname & ".DAT" For Binary As #f
Dim V(1 To totalElm) As Variant
Dim V2(1 To num_rows, 1 To 12) As Variant
For e = 1 To totalElm
V(e) = V2
Next e
' read records from the binary file
For a = 1 To totalLC
For e = 1 To totalElm
Do While Loc(f) < LOF(f)
Call ReadBinRecord(MyRecord, f, ElmType)
If MyRecord.MyBinaryRecordInfo1(1) = LC(a) Then
If MyRecord.MyBinaryRecordInfo1(2) = EID(e) Then
For j = 1 To totalbinrec
With MyRecord
V(e)(i, j) = .MyBinaryRecordInfo1(j)
End With
Next j
i = i + 1
Exit Do
End If
End If
Loop
Next e
Next a
Close #f ' close the file
' write out
For e = 1 To totalElm
Sheets(ElmType).Select
Cells(3, 1).Resize(num_rows, 12).Value = V(e)
Next e
End Sub
Sub ReadBinRecord(MyRecord As MyBinaryRecordInfo, f As Integer, ElmType As String)
' reads the next record from an open binary file
Dim intSize As Integer
For j = 1 To totalbinrec
With MyRecord
Get f, , intSize ' read the size of the ID field
.MyBinaryRecordInfo1(j) = String(intSize, " ") ' set the variable length
Get f, , .MyBinaryRecordInfo1(j) ' read the variable string field
End With
Next j
End Sub
If you don't know the number of rows then you just Redim Preserve the inner variants once every 500 rows or so.
As this writes everything out at the end, you might find it helpful to use Application.Statusbar = "my string" to write a progress message