Huge delay between ContentProvider and CursorLoader

Question

I am using a a CursorLoader and ContentProvider to read data from SQLite DB. The 'drugs' table has about 300,000 rows. I have created index on 'name' column in the 'drugs' table.

I have a SearchFragment where I search for drugs based on user query as follows:

public void update(String query, SearchView mSearchView, String mSearchType) {

    mQuery = query;

    Bundle b = new Bundle();
    b.putString("query", mQuery);

    mLoaderManager.restartLoader(Constants.DRUG_LOADER, b, this);
    Log.d(TAG, "Searching for " + mQuery);
}


public Loader<Cursor> onCreateLoader(int id, Bundle args) {
    Log.d(TAG, "onCreateLoader");

    return new CursorLoader(getActivity(), DrugsProvider.DRUGS_URI,
            null,
            ReapDbContract.Drugs.NAME + " like ?",
            new String[]{args.getString("query") + "%"},
            null
    );
}

@Override
public void onLoadFinished(Loader<Cursor> loader, Cursor c) {
    Log.d(TAG, "onLoadFinished");
    mAdapter.setCursor(c);
    mAdapter.notifyDataSetChanged();

    Log.d(TAG, "Done query for " + mQuery);
}

This is relevant part of DrugsProvider which runs the query:

@Override
public Cursor query(Uri uri, String[] projection, String where, String[] values, String sortOrder) {
    switch (sUriMatcher.match(uri)) {
        case DRUGS_TABLE:
            Cursor c = mDbHelper.query(Drugs.TABLE_NAME, projection, where, values, sortOrder);
            Log.d(TAG, "query done");
            return c;

        case DRUG_ROW:
            String id = uri.getLastPathSegment();
            return mDbHelper.getRow(Drugs.TABLE_NAME, id);

        default:
            throw new IllegalArgumentException("Invalid URI: " + uri);
    }
}

The DrugsHelper actually implements the query:

public Cursor query(String tableName, String[] projection, String where, String[] values, String sortOrder) {
    Log.d(TAG, "query: start: " + Arrays.toString(values));
    SQLiteDatabase db = getWritableDatabase();
    Log.d(TAG, "query: db");

    Cursor c = db.query(tableName, projection, where, values, null, null, sortOrder);
    Log.d(TAG, "query: done: " + Arrays.toString(values));

    return c;
}

The debug logs clearly tell that the actual DB query gets executed in a few milliseconds, but there is a delay of almost 500ms between the end of query and call to onLoadFinished. This is making the search extremely sluggish. Sometimes there is also a delay of about 500ms between call to onCreateLoader and when the provider actually runs the query. Here is a sample log:

================================================================

01-07 10:23:13.618 29288-29288/in.workcell.pos D/SearchFragment: onCreateLoader

01-07 10:23:13.627 29288-29288/in.workcell.pos D/SearchFragment: Searching for pari

01-07 10:23:13.632 29288-29524/in.workcell.pos D/DrugsHelper: query: start: [pari%]

01-07 10:23:13.632 29288-29524/in.workcell.pos D/DrugsHelper: query: db

01-07 10:23:13.632 29288-29524/in.workcell.pos D/DrugsHelper: query: done: [pari%]

01-07 10:23:13.632 29288-29524/in.workcell.pos D/DrugsProvider: query done

01-07 10:23:14.098 29288-29288/in.workcell.pos D/SearchFragment: onLoadFinished

01-07 10:23:14.098 29288-29288/in.workcell.pos D/SearchFragment: Done query for pari

================================================================

The DrugsProvider was done at 10:23:13.632, but onLoadFinished got called at 10:23:14.098, delay of 466ms! How can I debug what is causing this delay ?